Light-emitting device having multi-thickness transparent conductive layers

ABSTRACT

To provide a novel light-emitting device with high productivity, the light-emitting device includes a first light-emitting element, a second light-emitting element, and a third light-emitting element. In the first light-emitting element, a first lower electrode, a first transparent conductive layer, a first light-emitting layer, a second light-emitting layer, and an upper electrode are stacked in this order. In the second light-emitting element, a second lower electrode, a second transparent conductive layer, the first light-emitting layer, the second light-emitting layer, and the upper electrode are stacked in this order. In the third light-emitting element, a third lower electrode, a third transparent conductive layer, the second light-emitting layer, and the upper electrode are stacked in this order. The first transparent conductive layer includes a first region. The second transparent conductive layer includes a second region as thick as the third transparent conductive layer. The first region is thicker than the second region.

BACKGROUND OF THE INVENTION

1. Field of the Invention

One embodiment of the present invention relates to a light-emittingdevice, an electronic device, and a lighting device which include alight-emitting element in which a light-emitting layer capable ofemitting light by application of an electric field is provided between apair of electrodes.

Note that one embodiment of the present invention is not limited to theabove-described technical field. The technical field of one embodimentof the invention disclosed in this specification and the like relates toan object, a method, or a manufacturing method. In addition, oneembodiment of the present invention relates to a process, a machine,manufacture, or a composition of matter. Specifically, examples of thetechnical field of one embodiment of the present invention disclosed inthis specification include a semiconductor device, a display device, aliquid crystal display device, a light-emitting device, a lightingdevice, a power storage device, a memory device, a method for drivingany of them, and a method for manufacturing any of them.

2. Description of the Related Art

In recent years, a light-emitting element including a light-emittinglayer containing an organic compound between a pair of electrodes (e.g.,an organic EL element) has been actively developed. An electronic device(e.g., a smartphone) equipped with a light-emitting device in which thelight-emitting elements are arranged in a matrix is manufactured andcommercially available.

In an organic EL element, voltage application between a pair ofelectrodes, between which a light-emitting layer is interposed, causesrecombination of electrons and holes injected from the electrodes, whichbrings a light-emitting substance (an organic compound) into an excitedstate, and the return from the excited state to the ground state isaccompanied by light emission. Since the spectrum of light emitted froma light-emitting substance is peculiar to the light-emitting substance,use of different types of organic compounds as light-emitting substancesmakes it possible to provide light-emitting elements which exhibit lightof various colors.

In the case of light-emitting devices for displaying images, at leastthree-color light, i.e., red, green, and blue light is necessary forreproduction of full-color images. Furthermore, to enhance image qualitywith favorable color reproducibility, various efforts such as use of amicrocavity structure and a color filter have been made to improve colorpurity.

As a way to achieve full-color display, for example, there is a methodin which light-emitting layers for different colors are deposited inpixels side by side. The light-emitting layers are evaporated in onlypredetermined pixels using a shadow mask. In this case, to reduce costby reducing the number of steps, a structure in which layers except thelight-emitting layers, for example, a hole-transport layer, anelectron-transport layer, and a cathode are formed to be shared among aplurality of pixels is disclosed (e.g., see Patent Document 1).

REFERENCE Patent Document

[Patent Document 1] Japanese Published Patent Application No.2004-006362

SUMMARY OF THE INVENTION

In the structure disclosed in Patent Document 1, light-emitting layersfor different colors need to be deposited side by side, so that openingsof a shadow mask need to be arranged (aligned) at predeterminedpositions with high accuracy. For higher definition of thelight-emitting device, higher alignment accuracy is required. Thus, aproblem of a reduction in yield in manufacturing a light-emitting devicearises.

In view of the above-described problems, an object of one embodiment ofthe present invention is to provide a novel light-emitting device.Another object is to provide a novel light-emitting device with highproductivity and low power consumption. Another object is to provide anovel method for manufacturing a light-emitting device.

Note that the description of the above-described objects does notdisturb the existence of other objects. In one embodiment of the presentinvention, there is no need to achieve all of these objects. Otherobjects are apparent from and can be derived from the description of thespecification and the like.

One embodiment of the present invention is a light-emitting deviceincluding a first light-emitting element, a second light-emittingelement, and a third light-emitting element. The first light-emittingelement includes a first lower electrode, a first transparent conductivelayer over the first lower electrode, a first light-emitting layer overthe first transparent conductive layer, a second light-emitting layerover the first light-emitting layer, and an upper electrode over thesecond light-emitting layer. The second light-emitting element includesa second lower electrode, a second transparent conductive layer over thesecond lower electrode, the first light-emitting layer over the secondtransparent conductive layer, the second light-emitting layer over thefirst light-emitting layer, and the upper electrode over the secondlight-emitting layer. The third light-emitting element includes a thirdlower electrode, a third transparent conductive layer over the thirdlower electrode, the second light-emitting layer over the thirdtransparent conductive layer, and the upper electrode over the secondlight-emitting layer. The first transparent conductive layer includes afirst region. The second transparent conductive layer includes a secondregion as thick as the third transparent conductive layer. The firstregion is thicker than the second region.

Another embodiment of the present invention is a light-emitting deviceincluding a first light-emitting element, a second light-emittingelement, and a third light-emitting element. The first light-emittingelement includes a first lower electrode, a first transparent conductivelayer over the first lower electrode, a hole-injection layer over thefirst transparent conductive layer, a hole-transport layer over thehole-injection layer, a first light-emitting layer over thehole-transport layer, a second light-emitting layer over the firstlight-emitting layer, an electron-transport layer over the secondlight-emitting layer, an electron-injection layer over theelectron-transport layer, and an upper electrode over theelectron-injection layer. The second light-emitting element includes asecond lower electrode, a second transparent conductive layer over thesecond lower electrode, the hole-injection layer over the secondtransparent conductive layer, the hole-transport layer over thehole-injection layer, the first light-emitting layer over thehole-transport layer, the second light-emitting layer over the firstlight-emitting layer, the electron-transport layer over the secondlight-emitting layer, the electron-injection layer over theelectron-transport layer, and the upper electrode over theelectron-injection layer. The third light-emitting element includes athird lower electrode, a third transparent conductive layer over thethird lower electrode, the hole-injection layer over the thirdtransparent conductive layer, the hole-transport layer over thehole-injection layer, the second light-emitting layer over thehole-transport layer, the electron-transport layer over the secondlight-emitting layer, the electron-injection layer over theelectron-transport layer, and the upper electrode over theelectron-injection layer. The first transparent conductive layerincludes a first region. The second transparent conductive layerincludes a second region as thick as the third transparent conductivelayer. The first region is thicker than the second region.

Another embodiment of the present invention is a light-emitting deviceincluding a first light-emitting element, a second light-emittingelement, and a third light-emitting element. The first light-emittingelement includes a first lower electrode, a first transparent conductivelayer over the first lower electrode, an optical adjustment layer overthe first transparent conductive layer, a first light-emitting layerover the optical adjustment layer, a second light-emitting layer overthe first light-emitting layer, and an upper electrode over the secondlight-emitting layer. The second light-emitting element includes asecond lower electrode, a second transparent conductive layer over thesecond lower electrode, the optical adjustment layer over the secondtransparent conductive layer, the first light-emitting layer over theoptical adjustment layer, the second light-emitting layer over the firstlight-emitting layer, and the upper electrode over the secondlight-emitting layer. The third light-emitting element includes a thirdlower electrode, a third transparent conductive layer over the thirdlower electrode, the second light-emitting layer over the thirdtransparent conductive layer, and the upper electrode over the secondlight-emitting layer. The first transparent conductive layer includes afirst region. The second transparent conductive layer includes a secondregion as thick as the third transparent conductive layer. The firstregion is thicker than the second region.

Another embodiment of the present invention is a light-emitting deviceincluding a first light-emitting element, a second light-emittingelement, and a third light-emitting element. The first light-emittingelement includes a first lower electrode, a first transparent conductivelayer over the first lower electrode, a hole-injection layer over thefirst transparent conductive layer, a hole-transport layer over thehole-injection layer, an optical adjustment layer over thehole-transport layer, a first light-emitting layer over the opticaladjustment layer, a second light-emitting layer over the firstlight-emitting layer, an electron-transport layer over the secondlight-emitting layer, an electron-injection layer over theelectron-transport layer, and an upper electrode over theelectron-injection layer. The second light-emitting element includes asecond lower electrode, a second transparent conductive layer over thesecond lower electrode, the hole-injection layer over the secondtransparent conductive layer, the hole-transport layer over thehole-injection layer, the optical adjustment layer over thehole-transport layer, the first light-emitting layer over the opticaladjustment layer, the second light-emitting layer over the firstlight-emitting layer, the electron-transport layer over the secondlight-emitting layer, the electron-injection layer over theelectron-transport layer, and the upper electrode over theelectron-injection layer. The third light-emitting element includes athird lower electrode, a third transparent conductive layer over thethird lower electrode, the hole-injection layer over the thirdtransparent conductive layer, the hole-transport layer over thehole-injection layer, the second light-emitting layer over thehole-transport layer, the electron-transport layer over the secondlight-emitting layer, the electron-injection layer over theelectron-transport layer, and the upper electrode over theelectron-injection layer. The first transparent conductive layerincludes a first region. The second transparent conductive layerincludes a second region as thick as the third transparent conductivelayer. The first region is thicker than the second region.

In each of the above embodiments, a spectrum of light emitted from thefirst light-emitting element preferably includes at least one peak in awavelength range in which an emission wavelength is longer than or equalto 600 nm and shorter than or equal to 740 nm, a spectrum of lightemitted from the second light-emitting element preferably includes atleast one peak in a wavelength range in which an emission wavelength islonger than or equal to 480 nm and shorter than 600 nm, and a spectrumof light emitted from the third light-emitting element preferablyincludes at least one peak in a wavelength range in which an emissionwavelength is longer than or equal to 400 nm and shorter than 480 nm.

In each of the above embodiments, a distance between the first lowerelectrode and the first light-emitting layer is preferably larger than adistance between the second lower electrode and the first light-emittinglayer, and a distance between the second lower electrode and the secondlight-emitting layer is preferably larger than a distance between thethird lower electrode and the second light-emitting layer.

In each of the above embodiments, an optical path length between thefirst lower electrode and the first light-emitting layer is preferably3λ_(R)/4 (λ_(R) represents a wavelength of red light), an optical pathlength between the second lower electrode and the first light-emittinglayer is preferably 3λ_(G)/4 (λ_(G) represents a wavelength of greenlight), and an optical path length between the third lower electrode andthe second light-emitting layer is preferably 3λ_(B)/4 (λ_(B) representsa wavelength of blue light).

In each of the above embodiments, the optical adjustment layerpreferably has a hole-transport property.

In each of the above embodiments, the first light-emitting layerpreferably includes a phosphorescent material, and the secondlight-emitting layer preferably includes a fluorescent material.

Another embodiment of the present invention is a light-emitting deviceincluding a first light-emitting element, a second light-emittingelement, and a third light-emitting element. The first light-emittingelement includes a first lower electrode, a first transparent conductivelayer over the first lower electrode, an electron-injection layer overthe first transparent conductive layer, an electron-transport layer overthe electron-injection layer, a first light-emitting layer over theelectron-transport layer, a second light-emitting layer over the firstlight-emitting layer, a hole-transport layer over the secondlight-emitting layer, a hole-injection layer over the hole-transportlayer, and an upper electrode over the hole-injection layer. The secondlight-emitting element includes a second lower electrode, a secondtransparent conductive layer over the second lower electrode, theelectron-injection layer over the second transparent conductive layer,the electron-transport layer over the electron-injection layer, thefirst light-emitting layer over the electron-transport layer, the secondlight-emitting layer over the first light-emitting layer, thehole-transport layer over the second light-emitting layer, thehole-injection layer over the hole-transport layer, and the upperelectrode over the hole-injection layer. The third light-emittingelement includes a third lower electrode, a third transparent conductivelayer over the third lower electrode, the electron-injection layer overthe third transparent conductive layer, the electron-transport layerover the electron-injection layer, the second light-emitting layer overthe electron-transport layer, the hole-transport layer over the secondlight-emitting layer, the hole-injection layer over the hole-transportlayer, and the upper electrode over the hole-injection layer. The firsttransparent conductive layer includes a first region. The secondtransparent conductive layer includes a second region as thick as thethird transparent conductive layer. The first region is thicker than thesecond region.

Another embodiment of the present invention is a light-emitting deviceincluding a first light-emitting element, a second light-emittingelement, and a third light-emitting element. The first light-emittingelement includes a first lower electrode, a first transparent conductivelayer over the first lower electrode, an electron-injection layer overthe first transparent conductive layer, an electron-transport layer overthe electron-injection layer, an optical adjustment layer over theelectron-transport layer, a first light-emitting layer over the opticaladjustment layer, a second light-emitting layer over the firstlight-emitting layer, a hole-transport layer over the secondlight-emitting layer, a hole-injection layer over the hole-transportlayer, and an upper electrode over the hole-injection layer. The secondlight-emitting element includes a second lower electrode, a secondtransparent conductive layer over the second lower electrode, theelectron-injection layer over the second transparent conductive layer,the electron-transport layer over the electron-injection layer, theoptical adjustment layer over the electron-transport layer, the firstlight-emitting layer over the optical adjustment layer, the secondlight-emitting layer over the first light-emitting layer, thehole-transport layer over the second light-emitting layer, thehole-injection layer over the hole-transport layer, and the upperelectrode over the hole-injection layer. The third light-emittingelement includes a third lower electrode, a third transparent conductivelayer over the third lower electrode, the electron-injection layer overthe third transparent conductive layer, the electron-transport layerover the electron-injection layer, the second light-emitting layer overthe electron-transport layer, the hole-transport layer over the secondlight-emitting layer, the hole-injection layer over the hole-transportlayer, and the upper electrode over the hole-injection layer. The firsttransparent conductive layer includes a first region. The secondtransparent conductive layer includes a second region as thick as thethird transparent conductive layer. The first region is thicker than thesecond region.

In each of the above embodiments, a spectrum of light emitted from thefirst light-emitting element preferably includes at least one peak in awavelength range in which an emission wavelength is longer than or equalto 600 nm and shorter than or equal to 740 nm, a spectrum of lightemitted from the second light-emitting element preferably includes atleast one peak in a wavelength range in which an emission wavelength islonger than or equal to 480 nm and shorter than 600 nm, and a spectrumof light emitted from the third light-emitting element preferablyincludes at least one peak in a wavelength range in which an emissionwavelength is longer than or equal to 400 nm and shorter than 480 nm.

In each of the above embodiments, a distance between the first lowerelectrode and the first light-emitting layer is preferably larger than adistance between the second lower electrode and the first light-emittinglayer, and a distance between the second lower electrode and the secondlight-emitting layer is preferably larger than a distance between thethird lower electrode and the second light-emitting layer.

In each of the above embodiments, an optical path length between thefirst lower electrode and the first light-emitting layer is preferably3λ_(R)/4 (λ_(R) represents a wavelength of red light), an optical pathlength between the second lower electrode and the first light-emittinglayer is preferably 3λ_(G)/4 (λ_(G) represents a wavelength of greenlight), and an optical path length between the third lower electrode andthe second light-emitting layer is preferably 3λ_(B)/4 (λ_(B) representsa wavelength of blue light).

In each of the above embodiments, the optical adjustment layerpreferably has an electron-transport property.

In each of the above embodiments, the first light-emitting layerpreferably includes a phosphorescent material, and the secondlight-emitting layer preferably includes a fluorescent material.

One embodiment of the present invention includes, in its scope, anelectronic device including the light-emitting device in each of theabove embodiments and having a touch sensor function or a lightingdevice including the light-emitting device in each of the aboveembodiments and a housing. Note that a light-emitting device in thisspecification means an image display device or a light source (includinga lighting device). In addition, the light-emitting device includes, inits category, all of the following: a module in which a light-emittingdevice is connected to a connector such as a flexible printed circuit(FPC) or a tape carrier package (TCP), a module in which a printedwiring board is provided on the tip of a TCP, and a module in which anintegrated circuit (IC) is directly mounted on a light-emitting elementby a chip on glass (COG) method.

With one embodiment of the present invention, a novel light-emittingdevice can be provided. With one embodiment of the present invention, anovel light-emitting device with high productivity and low powerconsumption can be provided. With one embodiment of the presentinvention, a novel method for manufacturing a light-emitting device canbe provided.

Note that the description of these effects does not disturb theexistence of other effects. One embodiment of the present invention doesnot necessarily have all of these effects. Other effects are apparentfrom and can be derived from the description of the specification, thedrawings, the claims, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are a plan view and a cross-sectional view,respectively, illustrating a light-emitting device.

FIG. 2 is a cross-sectional view illustrating a light-emitting device.

FIGS. 3A and 3B are each a cross-sectional view illustrating alight-emitting device.

FIG. 4 is a plan view illustrating a light-emitting device.

FIG. 5 is a cross-sectional view illustrating a light-emitting device.

FIG. 6 is a cross-sectional view illustrating a light-emitting device.

FIG. 7 is a cross-sectional view illustrating a light-emitting device.

FIG. 8 is a cross-sectional view illustrating a light-emitting device.

FIGS. 9A to 9C are each a plan view illustrating a light-emittingdevice.

FIG. 10 is a cross-sectional view illustrating a light-emitting device.

FIG. 11 is a cross-sectional view illustrating a light-emitting device.

FIG. 12 is a cross-sectional view illustrating a light-emitting device.

FIG. 13 is a cross-sectional view illustrating a light-emitting device.

FIG. 14 is a cross-sectional view illustrating a light-emitting device.

FIG. 15 is a cross-sectional view illustrating a light-emitting device.

FIG. 16 is a cross-sectional view illustrating a light-emitting device.

FIG. 17 is a cross-sectional view illustrating a light-emitting device.

FIG. 18 is a cross-sectional view illustrating a light-emitting device.

FIG. 19 is a cross-sectional view illustrating a light-emitting device.

FIG. 20 is a cross-sectional view illustrating a transistor.

FIG. 21 is a cross-sectional view illustrating a light-emitting device.

FIG. 22 is a cross-sectional view illustrating a light-emitting device.

FIGS. 23A and 23B are cross-sectional views illustrating a method formanufacturing a light-emitting device.

FIGS. 24A and 24B are cross-sectional views illustrating the method formanufacturing the light-emitting device.

FIGS. 25A and 25B are cross-sectional views illustrating the method formanufacturing the light-emitting device.

FIGS. 26A and 26B are cross-sectional views illustrating a method formanufacturing a light-emitting device.

FIGS. 27A and 27B are cross-sectional views illustrating the method formanufacturing the light-emitting device.

FIGS. 28A and 28B are cross-sectional views illustrating the method formanufacturing the light-emitting device.

FIGS. 29A and 29B are each a cross-sectional view illustrating alight-emitting device.

FIGS. 30A and 30B are each a cross-sectional view illustrating alight-emitting device.

FIG. 31 is a cross-sectional view illustrating a light-emitting device.

FIG. 32 is a cross-sectional view illustrating a light-emitting device.

FIG. 33 is a cross-sectional view illustrating a light-emitting device.

FIG. 34 is a cross-sectional view illustrating a light-emitting device.

FIGS. 35A and 35B are a block diagram and a circuit diagram illustratinga display device.

FIGS. 36A and 36B are each a circuit diagram illustrating a pixelcircuit of a display device.

FIGS. 37A and 37B are each a circuit diagram illustrating a pixelcircuit of a display device.

FIGS. 38A and 38B are perspective views of an example of a touch panel.

FIGS. 39A to 39C are cross-sectional views of examples of a displaypanel and a touch sensor.

FIGS. 40A and 40B are each a cross-sectional view of an example of atouch panel.

FIGS. 41A and 41B are a block diagram and a timing chart of a touchsensor.

FIG. 42 is a circuit diagram of a touch sensor.

FIG. 43 is a perspective view of a display module.

FIGS. 44A to 44G illustrate electronic devices.

FIGS. 45A to 45C are a perspective view and cross-sectional viewsillustrating a light-emitting device.

FIGS. 46A to 46D are cross-sectional views illustrating a light-emittingdevice.

FIGS. 47A to 47C illustrate a lighting device and an electronic device.

FIGS. 48A to 48D are cross-sectional views each illustrating alight-emitting element in Examples 1 to 3.

FIGS. 49A and 49B show luminance-current density characteristics andluminance-voltage characteristics, respectively, of light-emittingelements in Example 1.

FIGS. 50A and 50B show current efficiency-luminance characteristics andemission spectra, respectively, of light-emitting elements in Example 1.

FIGS. 51A and 51B show luminance-current density characteristics andluminance-voltage characteristics, respectively, of light-emittingelements in Example 2.

FIGS. 52A and 52B show current efficiency-luminance characteristics andemission spectra, respectively, of light-emitting elements in Example 2.

FIGS. 53A and 53B show luminance-current density characteristics andluminance-voltage characteristics, respectively, of light-emittingelements in Example 3.

FIGS. 54A and 54B show current efficiency-luminance characteristics andemission spectra, respectively, of light-emitting elements in Example 3.

FIG. 55 shows normalized luminance-time characteristics oflight-emitting elements in Example 3.

FIGS. 56A to 56D are cross-sectional views each illustrating alight-emitting element in Reference Examples 1 to 3.

FIGS. 57A and 57B show luminance-current density characteristics andluminance-voltage characteristics, respectively, of light-emittingelements in Reference Example 1.

FIGS. 58A and 58B show current efficiency-luminance characteristics andemission spectra, respectively, of light-emitting elements in ReferenceExample 1.

FIGS. 59A and 59B show luminance-current density characteristics andluminance-voltage characteristics, respectively, of light-emittingelements in Reference Example 2.

FIGS. 60A and 60B show current efficiency-luminance characteristics andemission spectra, respectively, of light-emitting elements in ReferenceExample 2.

FIGS. 61A and 61B show luminance-current density characteristics andluminance-voltage characteristics, respectively, of light-emittingelements in Reference Example 3.

FIGS. 62A and 62B show current efficiency-luminance characteristics andemission spectra, respectively, of light-emitting elements in ReferenceExample 3.

FIG. 63 shows normalized luminance-time characteristics oflight-emitting elements in Reference Example 3.

FIG. 64 is a ¹H NMR chart of Ir(iBu5bpm)₂(acac).

FIG. 65 shows an ultraviolet-visible absorption spectrum and an emissionspectrum of Ir(iBu5bpm)₂(acac) in a dichloromethane solution.

FIG. 66 shows weight loss percentage of Ir(iBu5bpm)₂(acac).

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will be described below withreference to the drawings. However, the present invention is not limitedto description to be given below, and it is easily understood that modesand details thereof can be variously modified without departing from thepurpose and the scope of the present invention. Accordingly, the presentinvention should not be construed as being limited to the description ofthe embodiments below.

Note that the position, the size, the range, or the like of eachstructure shown in drawings and the like is not accurately representedin some cases for simplification. Therefore, the disclosed invention isnot necessarily limited to the position, the size, the range, or thelike disclosed in the drawings and the like.

Note that the ordinal numbers such as “first”, “second”, and the like inthis specification and the like are used for convenience and do notdenote the order of steps or the stacking order of layers. Therefore,for example, description can be made even when “first” is replaced with“second” or “third”, as appropriate. In addition, the ordinal numbers inthis specification and the like are not necessarily the same as thosewhich specify one embodiment of the present invention.

In describing structures of the invention with reference to the drawingsin this specification and the like, common reference numerals are usedfor the same portions in different drawings.

Embodiment 1

In this embodiment, a light-emitting device of one embodiment of thepresent invention and a method for manufacturing the light-emittingdevice will be described below with reference to FIGS. 1A and 1B, FIG.2, FIGS. 3A and 3B, FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG. 8, FIGS. 9A to9C, FIG. 10, FIG. 11, FIG. 12, FIG. 13, FIG. 14, FIG. 15, FIG. 16, FIG.17, FIG. 18, FIG. 19, FIG. 20, FIG. 21, FIG. 22, FIGS. 23A and 23B,FIGS. 24A and 24B, FIGS. 25A and 25B, FIGS. 26A and 26B, FIGS. 27A and27B, FIGS. 28A and 28B, FIGS. 29A and 29B, FIGS. 30A and 30B, FIG. 31,FIG. 32, FIG. 33, and FIG. 34.

Structural Example 1 of Light-Emitting Device

FIG. 1A is a plan view illustrating an example of a light-emittingdevice of one embodiment of the present invention. FIG. 1B is across-sectional view along dashed-dotted line X1-Y1 in FIG. 1A.

A light-emitting device 100 illustrated in FIGS. 1A and 1B includes afirst light-emitting element 101R, a second light-emitting element 101G,and a third light-emitting element 101B. The first light-emittingelement 101R includes a first lower electrode 104R, a first transparentconductive layer 106R over the first lower electrode 104R, a firstlight-emitting layer 110 over the first transparent conductive layer106R, a second light-emitting layer 112 over the first light-emittinglayer 110, and an upper electrode 114 over the second light-emittinglayer 112. The second light-emitting element 101G includes a secondlower electrode 104G, a second transparent conductive layer 106G overthe second lower electrode 104G, the first light-emitting layer 110 overthe second transparent conductive layer 106G, the second light-emittinglayer 112 over the first light-emitting layer 110, and the upperelectrode 114 over the second light-emitting layer 112. The thirdlight-emitting element 101B includes a third lower electrode 104B, athird transparent conductive layer 106B over the third lower electrode104B, the second light-emitting layer 112 over the third transparentconductive layer 106B, and the upper electrode 114 over the secondlight-emitting layer 112.

Note that in the light-emitting device 100, the lower electrodes (thefirst lower electrode 104R, the second lower electrode 104G, and thethird lower electrode 104B) each function as an anode, and the upperelectrode 114 functions as a cathode. The lower electrode has a functionof reflecting light. However, the structure of the lower electrode andthe upper electrode is not limited thereto and, for example, the lowerelectrode may function as a cathode and the upper electrode may functionas an anode.

The second transparent conductive layer 106G and the third transparentconductive layer 106B are formed with substantially the samethicknesses. For example, in the case where the second transparentconductive layer 106G and the third transparent conductive layer 106Bare formed through a step of processing one transparent conductive film,they have substantially the same thicknesses or include regions havingsubstantially the same thicknesses. In this specification and the like,the term “substantially the same thicknesses” includes the case where,between two compared films, the thickness of one film is greater than orequal to −20% and less than or equal to +20% or greater than or equal to−10% and less than or equal to +10% with respect to the thickness of theother film. In addition, the thickness of the first transparentconductive layer 106R is greater than that of each of the secondtransparent conductive layer 106G and the third transparent conductivelayer 106B. In other words, the first transparent conductive layer 106Rincludes a first region and the second transparent conductive layer 106Gincludes a second region having the same thickness as the thirdtransparent conductive layer 106B, and the first region is thicker thanthe second region. With such a structure, a distance between the lowerelectrode and the light-emitting layer or an optical path length betweenthe lower electrode and the light-emitting layer can be adjusted in eachof the light-emitting elements.

Specifically, the distance between the first lower electrode 104R andthe first light-emitting layer 110 is larger than the distance betweenthe second lower electrode 104G and the first light-emitting layer 110,and the distance between the second lower electrode 104G and the secondlight-emitting layer 112 is larger than the distance between the thirdlower electrode 104B and the second light-emitting layer 112.

In the case where the distances between the lower electrodes and thelight-emitting layers have the above-described relations, it ispreferable that an optical path length between the first lower electrode104R and the first light-emitting layer 110 be 3λ_(R)/4 (λ_(R)represents a wavelength of red light), that an optical path lengthbetween the second lower electrode 104G and the first light-emittinglayer 110 be 3λ_(G)/4 (λ_(G) represents a wavelength of green light),and that an optical path length between the third lower electrode 104Band the second light-emitting layer 112 be 3λ_(B)/4 (λ_(B) represents awavelength of blue light).

In the light-emitting device 100, the thickness of the secondtransparent conductive layer 106G is the same as that of the thirdtransparent conductive layer 106B, and the thickness of the firsttransparent conductive layer 106R is greater than that of each of thesecond transparent conductive layer 106G and the third transparentconductive layer 106B. The above-described optical path length of thethird light-emitting element 101B is possible because the firstlight-emitting layer 110 is not provided. With the above-describedoptical path lengths, light in a red wavelength range, light in a greenwavelength range, and light in a blue wavelength range can beefficiently extracted from the first light-emitting element 101R, thesecond light-emitting element 101G, and the third light-emitting element101B, respectively.

Note that, to be exact, the optical path length between each of thelower electrodes (the first lower electrode 104R and the second lowerelectrode 104G) and the first light-emitting layer 110 is represented bythe product of the refractive index and the thickness between areflective region in the lower electrode and the first light-emittinglayer 110. However, it is difficult to precisely determine thereflection region in the lower electrode or a light-emitting region inthe first light-emitting layer 110; therefore, it is presumed that theabove-described effect can be sufficiently achieved wherever thereflection region and the light-emitting region may be set in the lowerelectrode and the first light-emitting layer 110, respectively. Notethat the same applies to the optical path length between the third lowerelectrode 104B and the second light-emitting layer 112.

A spectrum of light emitted from the first light-emitting element 101Rincludes at least one peak in the red wavelength range, a spectrum oflight emitted from the second light-emitting element 101G includes atleast one peak in the green wavelength range, and a spectrum of lightemitted from the third light-emitting element 101B includes at least onepeak in the blue wavelength range. Accordingly, by the firstlight-emitting element 101R, the second light-emitting element 101G, andthe third light-emitting element 101B, full-color display can beperformed. Note that in this specification and the like, an emissionwavelength in the red wavelength range is longer than or equal to 600 nmand shorter than or equal to 740 nm, an emission wavelength in the greenwavelength range is longer than or equal to 480 nm and shorter than 600nm, and an emission wavelength in the blue wavelength range is longerthan or equal to 400 nm and shorter than 480 nm.

In FIG. 1B, light in a red (R) wavelength range, light in a green (G)wavelength range, and light in a blue (B) wavelength range emitted tothe outside are schematically shown by arrows (R, G, and B) with brokenlines. The same applies to light-emitting devices described later. Thus,the light-emitting device 100 illustrated in FIGS. 1A and 1B is of atop-emission type in which light emitted from light-emitting elements isextracted to the side opposite to the substrate 102 side where thelight-emitting elements are formed. However, one embodiment of thepresent invention is not limited to this type, and may be of abottom-emission type in which light emitted from light-emitting elementsis extracted to the substrate side where the light-emitting elements areformed, or a dual-emission type in which light emitted fromlight-emitting elements is extracted in both top and bottom directionsof the substrate 102 where the light-emitting elements are formed.

Moreover, in the light-emitting device 100 illustrated in FIGS. 1A and1B, the first light-emitting layer 110 is shared between the firstlight-emitting element 101R and the second light-emitting element 101G,and the second light-emitting layer 112 is shared between the firstlight-emitting element 101R, the second light-emitting element 101G, andthe third light-emitting element 101B. By sharing the firstlight-emitting layer 110 or the second light-emitting layer 112 betweenthe light-emitting elements, the productivity in formation of thelight-emitting elements can be increased. Specifically, in manufacturingthe light-emitting elements of the light-emitting device 100, only onestep (the step for depositing the first light-emitting layer 110) isrequired to form layers in selected pixels, so that the productivity canbe increased.

Note that in the first light-emitting element 101R and the secondlight-emitting element 101G, the second light-emitting layer 112 doesnot contribute to light emission. For example, for the secondlight-emitting layer 112, a material with a high electron-transportproperty and a low hole-transport property or a material having a lowerhighest occupied molecular orbital (HOMO) level than a material used forthe first light-emitting layer 110 is used. In other words, in each ofthe first light-emitting element 101R and the second light-emittingelement 101G, the second light-emitting layer 112 functions as anelectron-transport layer.

The first light-emitting layer 110 includes a phosphorescent material.The second light-emitting layer 112 includes a fluorescent material.With such a structure, a novel light-emitting device with high luminousefficiency and high reliability can be provided. For example, the firstlight-emitting layer 110 can be formed using a phosphorescent materialemitting light in a green wavelength range, and the secondlight-emitting layer 112 can be formed using a fluorescent materialemitting light in a blue wavelength range. However, the materials thatcan be used for the first light-emitting layer 110 and the secondlight-emitting layer 112 are not limited to the above. For example, aphosphorescent material may be used for the second light-emitting layer112.

Although the first light-emitting element 101R, the secondlight-emitting element 101G, and the third light-emitting element 101Bare provided in a stripe arrangement in FIG. 1A as an example, they maybe provided in any other arrangement. For example, a delta arrangementillustrated in FIG. 9A, a pentile arrangement illustrated in FIG. 9B, ora pixel arrangement illustrated in FIG. 9C may be employed as thearrangement of the light-emitting elements. Note that FIGS. 9A to 9C areplan views each illustrating an example of the light-emitting device.

With the above-described structure, in manufacturing the light-emittingelements, the number of steps for forming layers in selected pixels issmall; thus, a light-emitting device with increased productivity can beprovided. The light-emitting elements of the light-emitting device havelow power consumption because of their high luminous efficiency.Moreover, the light-emitting elements have high reliability. Therefore,a novel light-emitting device with high productivity and low powerconsumption can be provided.

Next, a different mode of the light-emitting device 100 illustrated inFIGS. 1A and 1B is described with reference to FIG. 2. Note that FIG. 2is a cross-sectional view along dashed dotted line X1-Y1 in FIG. 1A.

The light-emitting device 100 illustrated in FIG. 2 includes the firstlight-emitting element 101R, the second light-emitting element 101G, andthe third light-emitting element 101B. The first light-emitting element101R includes the first lower electrode 104R, the first transparentconductive layer 106R over the first lower electrode 104R, ahole-injection layer 131 over the first transparent conductive layer106R, a hole-transport layer 132 over the hole-injection layer 131, thefirst light-emitting layer 110 over the hole-transport layer 132, thesecond light-emitting layer 112 over the first light-emitting layer 110,an electron-transport layer 133 over the second light-emitting layer112, an electron-injection layer 134 over the electron-transport layer133, and the upper electrode 114 over the electron-injection layer 134.The second light-emitting element 101G includes the second lowerelectrode 104G, the second transparent conductive layer 106G over thesecond lower electrode 104G, the hole-injection layer 131 over thesecond transparent conductive layer 106G, the hole-transport layer 132over the hole-injection layer 131, the first light-emitting layer 110over the hole-transport layer 132, the second light-emitting layer 112over the first light-emitting layer 110, the electron-transport layer133 over the second light-emitting layer 112, the electron-injectionlayer 134 over the electron-transport layer 133, and the upper electrode114 over the electron-injection layer 134. The third light-emittingelement 101B includes the third lower electrode 104B, the thirdtransparent conductive layer 106B over the third lower electrode 104B,the hole-injection layer 131 over the third transparent conductive layer106B, the hole-transport layer 132 over the hole-injection layer 131,the second light-emitting layer 112 over the hole-transport layer 132,the electron-transport layer 133 over the second light-emitting layer112, the electron-injection layer 134 over the electron-transport layer133, and the upper electrode 114 over the electron-injection layer 134.

As in the light-emitting device 100 illustrated in FIG. 2, thehole-injection layer 131 and the hole-transport layer 132 are providedbetween each of the transparent conductive layers (the first transparentconductive layer 106R, the second transparent conductive layer 106G, andthe third transparent conductive layer 106B) and the firstlight-emitting layer 110 or the second light-emitting layer 112, and theelectron-transport layer 133 and the electron-injection layer 134 areprovided between the second light-emitting layer 112 and the upperelectrode 114. Note that without limitation to the structure illustratedin FIG. 2, the light-emitting device 100 may include at least oneselected from the hole-injection layer 131, the hole-transport layer132, the electron-transport layer 133, and the electron-injection layer134. Alternatively, although not illustrated in FIG. 2, a functionallayer having a function of reducing a carrier injection barrier may beprovided.

Here, the second light-emitting layers 112 preferably has anelectron-transport property so that carriers are recombined efficientlyin the first light-emitting layer 110 in each of the firstlight-emitting element 101R and the second light-emitting element 101G.In other words, in the case where the second light-emitting layer 112includes a host material and a guest material (a light-emittingmaterial), it is preferable that the host material have anelectron-transport property and that the guest material have a hole-trapproperty. From the same point of view, it is preferable that the firstlight-emitting layer 110 have an electron-transport property; however,it is difficult to optimize the optical path length when a recombinationregion is localized on the hole-transport layer 132 side (this isbecause the optical thickness of the first light-emitting layer 110 isapproximately λ_(G)-λ_(B), in which case the optical path length betweenthe lower electrode 104G and the interface between the firstlight-emitting layer 110 and the hole-transport layer 132 deviates from3λ_(G)/4). To optimize this deviation, it is necessary that the firstlight-emitting layer 110 have not only an electron-transport propertybut also an appropriate hole-transport property that can prevent passageof holes to the second light-emitting layer 112. That is, it ispreferable that the first light-emitting layer 110 have a bipolarproperty. Accordingly, for example, it is preferable that the firstlight-emitting layer 110 include at least a hole-transport material, anelectron-transport material, and a light-emitting material.

Next, other different modes of the light-emitting device 100 illustratedin FIGS. 1A and 1B are described with reference to FIGS. 3A and 3B. Notethat FIGS. 3A and 3B are each a cross-sectional view along dashed dottedline X1-Y1 in FIG. 1A.

In the light-emitting device 100 illustrated in FIG. 3A, an opticaladjustment layer 108 is provided in addition to the components of thelight-emitting device 100 illustrated in FIG. 1B. Specifically, thefirst light-emitting element 101R includes the optical adjustment layer108 between the first transparent conductive layer 106R and the firstlight-emitting layer 110. The second light-emitting element 101Gincludes the optical adjustment layer 108 between the second transparentconductive layer 106G and the first light-emitting layer 110.

In the light-emitting device 100 illustrated in FIG. 3B, the opticaladjustment layer 108 is provided in addition to the components of thelight-emitting device 100 illustrated in FIG. 2. Specifically, the firstlight-emitting element 101R includes the optical adjustment layer 108between the hole-transport layer 132 and the first light-emitting layer110. The second light-emitting element 101G includes the opticaladjustment layer 108 between the hole-transport layer 132 and the firstlight-emitting layer 110.

As illustrated in FIG. 3A, with the structure provided with the opticaladjustment layer 108, an optical path length between each of the lowerelectrodes (the first lower electrode 104R and the second lowerelectrode 104G) and the first light-emitting layer 110 can be adjusted.As illustrated in FIG. 3B, with the structure provided with the opticaladjustment layer 108, an optical path length between each of the lowerelectrodes (the first lower electrode 104R and the second lowerelectrode 104G) and the upper electrode 114 can be adjusted. It ispossible not to provide the optical adjustment layer 108 in the casewhere the optical path length between the lower electrode and the upperelectrode 114 can be adjusted by each of the transparent conductivelayers (the first transparent conductive layer 106R, the secondtransparent conductive layer 106G, and the third transparent conductivelayer 106B), the first light-emitting layer 110, and/or the secondlight-emitting layer 112. However, the optical adjustment layer 108 ispreferred to be provided because the optical path length can be adjustedeasily.

Furthermore, in manufacturing the light-emitting device 100 illustratedin FIGS. 3A and 3B, only one step is required to form layers in selectedpixels when the optical adjustment layer 108 and the firstlight-emitting layer 110 are formed consecutively. That is, there is noincrease in the number of steps for forming layers in selected pixelsthat is accompanied by addition of the optical adjustment layer 108.

The optical adjustment layer 108 preferably has a hole-transportproperty. For example, when the optical adjustment layer 108 is formedusing a material with a high hole-transport property, holes can bepreferably transported to the first light-emitting layer 110; thus, thefirst light-emitting layer 110 can have high luminous efficiency.

Next, other different modes of the light-emitting device 100 illustratedin FIGS. 1A and 1B are described with reference to FIG. 4, FIG. 5, FIG.6, FIG. 7, and FIG. 8. FIG. 4 is a plan view illustrating an example ofa light-emitting device of one embodiment of the present invention. Notethat FIGS. 5 to 8 are each a cross-sectional view along dashed dottedline X2-Y2 in FIG. 4.

The light-emitting device 100 illustrated in FIG. 5 includes a partition136 and a substrate 152 in addition to the components of thelight-emitting device 100 illustrated in FIG. 3B. The partitions 136 areprovided at outer portions of the light-emitting elements and have afunction of covering the end portions of either or both of the lowerelectrodes and the transparent conductive layers of the light-emittingelements. The substrate 152 is provided with a light-blocking layer 154,a first optical element 156R, a second optical element 156G, and a thirdoptical element 156B. The light-blocking layer 154 is provided tooverlap with the partition 136. The first optical element 156R, thesecond optical element 156G, and the third optical element 156B areprovided to overlap with the first light-emitting element 101R, thesecond light-emitting element 101G, and the third light-emitting element101B, respectively.

In the light-emitting device 100 illustrated in FIG. 6, the secondoptical element 156G and the third optical element 156B of thelight-emitting device 100 illustrated in FIG. 5 are not provided. In thelight-emitting device 100 illustrated in FIG. 7, the third opticalelement 156B of the light-emitting device 100 illustrated in FIG. 5 isnot provided. In the light-emitting device 100 illustrated in FIG. 8,the second optical element 156G of the light-emitting device 100illustrated in FIG. 5 is not provided.

With the use of a phosphorescent material emitting light in a greenwavelength range for the first light-emitting layer 110 and afluorescent material emitting light in a blue wavelength range for thesecond light-emitting layer 112, it is possible not to provide anoptical element in at least one of the regions overlapping with thesecond light-emitting element 101G and the third light-emitting element101B. With a structure in which an optical element is not provided in atleast one of the regions overlapping with the second light-emittingelement 101G and the third light-emitting element 101B, the powerconsumption of the light-emitting device 100 can be reduced. With astructure in which the third optical element 156G is not provided, powerconsumption can be reduced more effectively particularly when afluorescent material emitting light in a blue wavelength range is usedfor the third light-emitting element 101B. Note that to prevent externallight reflection, the structure illustrated in FIG. 5 in which thelight-emitting elements are all provided with the optical element ispreferred.

Structural Example 2 of Light-Emitting Device

Next, structures different from the above-described light-emittingdevices are described with reference to FIGS. 1A and 1B, FIG. 4, FIG.10, FIG. 11, FIG. 12, FIG. 13, FIG. 14, and FIG. 15.

FIG. 1A is a plan view illustrating an example of a light-emittingdevice of one embodiment of the present invention. FIG. 10 is across-sectional view along dashed-dotted line X1-Y1 in FIG. 1A.

A light-emitting device 100A includes the first light-emitting element101R, the second light-emitting element 101G, and the thirdlight-emitting element 101B. The first light-emitting element 101Rincludes the first lower electrode 104R, the first transparentconductive layer 106R over the first lower electrode 104R, theelectron-injection layer 134 over the first transparent conductive layer106R, the electron-transport layer 133 over the electron-injection layer134, the first light-emitting layer 110 over the electron-transportlayer 133, the second light-emitting layer 112 over the firstlight-emitting layer 110, the hole-transport layer 132 over the secondlight-emitting layer 112, the hole-injection layer 131 over thehole-transport layer 132, and the upper electrode 114 over thehole-injection layer 131. The second light-emitting element 101Gincludes the second lower electrode 104G, the second transparentconductive layer 106G over the second lower electrode 104G, theelectron-injection layer 134 over the second transparent conductivelayer 106G, the electron-transport layer 133 over the electron-injectionlayer 134, the first light-emitting layer 110 over theelectron-transport layer 133, the second light-emitting layer 112 overthe first light-emitting layer 110, the hole-transport layer 132 overthe second light-emitting layer 112, the hole-injection layer 131 overthe hole-transport layer 132, and the upper electrode 114 over thehole-injection layer 131. The third light-emitting element 101B includesthe third lower electrode 104B, the third transparent conductive layer106B over the third lower electrode 104B, the electron-injection layer134 over the third transparent conductive layer 106B, theelectron-transport layer 133 over the electron-injection layer 134, thesecond light-emitting layer 112 over the electron-transport layer 133,the hole-transport layer 132 over the second light-emitting layer 112,the hole-injection layer 131 over the hole-transport layer 132, and theupper electrode 114 over the hole-injection layer 131.

Note that in the light-emitting device 100A, the lower electrodes (thefirst lower electrode 104R, the second lower electrode 104G, and thethird lower electrode 104B) each function as a cathode, and the upperelectrode 114 functions as an anode. The lower electrode has a functionof reflecting light.

The second transparent conductive layer 106G and the third transparentconductive layer 106B are formed with substantially the samethicknesses. For example, in the case where the second transparentconductive layer 106G and the third transparent conductive layer 106Bare formed through a step of processing one transparent conductive film,they have substantially the same thicknesses or include regions havingsubstantially the same thicknesses. In this specification and the like,the term “substantially the same thicknesses” includes the case where,between two compared films, the thickness of one film is greater than orequal to −20% and less than or equal to +20% or greater than or equal to−10% and less than or equal to +10% of the thickness of the other film.In addition, the thickness of the first transparent conductive layer106R is greater than that of each of the second transparent conductivelayer 106G and the third transparent conductive layer 106B. In otherwords, the first transparent conductive layer 106R includes a firstregion and the second transparent conductive layer 106G includes asecond region having the same thickness as the third transparentconductive layer 106B, and the first region is thicker than the secondregion. With such a structure, a distance between the lower electrodeand the light-emitting layer or an optical path length between the lowerelectrode and the light-emitting layer can be adjusted in each of thelight-emitting elements.

Specifically, the distance between the first lower electrode 104R andthe first light-emitting layer 110 is larger than the distance betweenthe second lower electrode 104G and the first light-emitting layer 110,and the distance between the second lower electrode 104G and the secondlight-emitting layer 112 is larger than the distance between the thirdlower electrode 104B and the second light-emitting layer 112.

In the case where the distances between the lower electrodes and thelight-emitting layers have the above-described relations, it ispreferable that an optical path length between the first lower electrode104R and the first light-emitting layer 110 be 3λ_(B)/4 (λ_(R)represents a wavelength of red light), that an optical path lengthbetween the second lower electrode 104G and the first light-emittinglayer 110 be 3λ_(G)/4 (λ_(G) represents a wavelength of green light),and that an optical path length between the third lower electrode 104Band the second light-emitting layer 112 be 3λ_(B)/4 (λ_(B) represents awavelength of blue light).

In the light-emitting device 100A, the thickness of the secondtransparent conductive layer 106G is the same as that of the thirdtransparent conductive layer 106B, and the thickness of the firsttransparent conductive layer 106R is greater than that of each of thesecond transparent conductive layer 106G and the third transparentconductive layer 106B. The above-described optical path length of thethird light-emitting element 101B is possible because the firstlight-emitting layer 110 is not provided. With the above-describedoptical path lengths, light in a red wavelength range, light in a greenwavelength range, and light in a blue wavelength range can beefficiently extracted from the first light-emitting element 101R, thesecond light-emitting element 101G, and the third light-emitting element101B, respectively.

Note that, to be exact, the optical path length between each of thelower electrodes (the first lower electrode 104R and the second lowerelectrode 104G) and the first light-emitting layer 110 is represented bythe product of the refractive index and the thickness between areflective region in the lower electrode and the first light-emittinglayer 110. However, it is difficult to precisely determine thereflection region in the lower electrode or a light-emitting region inthe first light-emitting layer 110; therefore, it is presumed that theabove-described effect can be sufficiently achieved wherever thereflection region and the light-emitting region may be set in the lowerelectrode and the first light-emitting layer 110, respectively. Notethat the same applies to the optical path length between the third lowerelectrode 104B and the second light-emitting layer 112.

A spectrum of light emitted from the first light-emitting element 101Rincludes at least one peak in the red wavelength range, a spectrum oflight emitted from the second light-emitting element 101G includes atleast one peak in the green wavelength range, and a spectrum of lightemitted from the third light-emitting element 101B includes at least onepeak in the blue wavelength range. Accordingly, by the firstlight-emitting element 101R, the second light-emitting element 101G, andthe third light-emitting element 101B, full-color display can beperformed. Note that in this specification and the like, an emissionwavelength in the red wavelength range is longer than or equal to 600 nmand shorter than or equal to 740 nm, an emission wavelength in the greenwavelength range is longer than or equal to 480 nm and shorter than 600nm, and an emission wavelength in the blue wavelength range is longerthan or equal to 400 nm and shorter than 480 nm.

In FIG. 10, light in a red (R) wavelength range, light in a green (G)wavelength range, and light in a blue (B) wavelength range emitted tothe outside are schematically shown by arrows (R, G, and B) with brokenlines. The same applies to light-emitting devices described later. Thus,the light-emitting device 100 illustrated in FIGS. 1A and 1B and thelight-emitting device 100A illustrated in FIG. 10 are each of atop-emission type in which light emitted from light-emitting elements isextracted to the side opposite to the substrate 102 side where thelight-emitting elements are formed. However, one embodiment of thepresent invention is not limited to this type, and may be of abottom-emission type in which light emitted from light-emitting elementsis extracted to the substrate side where the light-emitting elements areformed, or a dual-emission type in which light emitted fromlight-emitting elements is extracted in both top and bottom directionsof the substrate 102 where the light-emitting elements are formed.

Moreover, in the light-emitting device 100A, the first light-emittinglayer 110 is shared between the first light-emitting element 101R andthe second light-emitting element 101G, and the second light-emittinglayer 112 is shared between the first light-emitting element 101R, thesecond light-emitting element 101G, and the third light-emitting element101B. By sharing the first light-emitting layer 110 or the secondlight-emitting layer 112 between the light-emitting elements, theproductivity in formation of the light-emitting elements can beincreased. Specifically, in manufacturing the light-emitting elements ofthe light-emitting device 100A, only one step (the step for depositingthe first light-emitting layer 110) is required to form layers inselected pixels, so that the productivity can be increased.

Note that in the first light-emitting element 101R and the secondlight-emitting element 101G, the second light-emitting layer 112 doesnot contribute to light emission. For example, for the secondlight-emitting layer 112, a material with a high hole-transport propertyand a low electron-transport property or a material having a higher HOMOlevel than a material used for the first light-emitting layer 110 isused. In other words, in each of the first light-emitting element 101Rand the second light-emitting element 101G, the second light-emittinglayer 112 functions as a hole-transport layer. Thus, the secondlight-emitting layer 112 preferably has a hole-transport property. Inother words, in the case where the second light-emitting layer 112includes a host material and a guest material (light-emittingmaterials), it is preferable that the host material have ahole-transport property and that the guest material have anelectron-trap property. From the same point of view, it is preferablethat the first light-emitting layer 110 have a hole-transport property;however, it is difficult to optimize the optical path length when arecombination region is localized on the electron-transport layer 133side (this is because the optical thickness of the first light-emittinglayer 110 is approximately λ_(G)-λ_(B), in which case the optical pathlength between the lower electrode 104G and the interface between thefirst light-emitting layer 110 and the electron-transport layer 133deviates from 3λ_(G)/4). To optimize this deviation, it is necessarythat the first light-emitting layer 110 have not only a hole-transportproperty but also an appropriate electron-transport property that canprevent passage of electrons to the second light-emitting layer 112.That is, it is preferable that the first light-emitting layer 110 have abipolar property. Accordingly, for example, the first light-emittinglayer 110 preferably includes at least a hole-transport material, anelectron-transport material, and a light-emitting material.

The first light-emitting layer 110 includes a phosphorescent material.The second light-emitting layer 112 includes a fluorescent material.With such a structure, a novel light-emitting device with high luminousefficiency and high reliability can be provided. For example, the firstlight-emitting layer 110 can be formed using a phosphorescent materialemitting light in a green wavelength range, and the secondlight-emitting layer 112 can be formed using a fluorescent materialemitting light in a blue wavelength range. However, the materials thatcan be used for the first light-emitting layer 110 and the secondlight-emitting layer 112 are not limited to the above. For example, aphosphorescent material may be used for the second light-emitting layer112.

With the above-described structure, in manufacturing the light-emittingelements, the number of steps for forming layers in selected pixels issmall; thus, a light-emitting device with increased productivity can beprovided. The light-emitting elements of the light-emitting device havelow power consumption because of their high luminous efficiency.Moreover, the light-emitting elements have high reliability. Therefore,a novel light-emitting device with high productivity and low powerconsumption can be provided.

Next, a different mode of the light-emitting device 100A illustrated inFIG. 10 is described with reference to FIG. 11. Note that FIG. 11 is across-sectional view along dashed dotted line X1-Y1 in FIG. 1A.

In the light-emitting device 100A illustrated in FIG. 11, the opticaladjustment layer 108 is provided in addition to the components of thelight-emitting device 100A illustrated in FIG. 10. Specifically, thefirst light-emitting element 101R includes the optical adjustment layer108 between the electron-transport layer 133 and the firstlight-emitting layer 110. The second light-emitting element 101Gincludes the optical adjustment layer 108 between the electron-transportlayer 133 and the first light-emitting layer 110.

As illustrated in FIG. 11, with the structure provided with the opticaladjustment layer 108, an optical path length between each of the lowerelectrodes (the first lower electrode 104R and the second lowerelectrode 104G) and the first light-emitting layer 110 can be adjusted.It is possible not to provide the optical adjustment layer 108 in thecase where the optical path length between the lower electrode and theupper electrode 114 can be adjusted by each of the transparentconductive layers (the first transparent conductive layer 106R, thesecond transparent conductive layer 106G, and the third transparentconductive layer 106B), the first light-emitting layer 110, and/or thesecond light-emitting layer 112. However, the optical adjustment layer108 is preferred to be provided because the optical path length can beadjusted easily.

Furthermore, in manufacturing the light-emitting device 100A illustratedin FIG. 11, only one step is required to form layers in selected pixelswhen the optical adjustment layer 108 and the first light-emitting layer110 are formed consecutively. That is, there is no increase in thenumber of steps for forming layers in selected pixels that isaccompanied by addition of the optical adjustment layer 108.

The optical adjustment layer 108 of the light-emitting device 100Aillustrated in FIG. 11 preferably has an electron-transport property.For example, when the optical adjustment layer 108 is formed using amaterial with a high electron-transport property, electrons can bepreferably transported to the first light-emitting layer 110; thus, thefirst light-emitting layer 110 can have high luminous efficiency.

Next, other different modes of the light-emitting device 100Aillustrated in FIG. 10 are described with reference to FIG. 4, FIG. 12,FIG. 13, FIG. 14, and FIG. 15. Note that FIGS. 12 to 15 are each across-sectional view along dashed dotted line X2-Y2 in FIG. 4. Note thatFIG. 4 is a plan view of the light-emitting device 100 but may also beused as a plan view of the light-emitting device 100A.

The light-emitting device 100A illustrated in FIG. 12 includes thepartition 136 and the substrate 152 in addition to the components of thelight-emitting device 100A illustrated in FIG. 11. The partitions 136are provided at outer portions of the light-emitting elements and have afunction of covering the end portions of either or both of the lowerelectrodes and the transparent conductive layers of the light-emittingelements. The substrate 152 is provided with the light-blocking layer154, the first optical element 156R, the second optical element 156G,and the third optical element 156B. The light-blocking layer 154 isprovided to overlap with the partition 136. The first optical element156R, the second optical element 156G, and the third optical element156B are provided to overlap with the first light-emitting element 101R,the second light-emitting element 101G, and the third light-emittingelement 101B, respectively.

In the light-emitting device 100A illustrated in FIG. 13, the secondoptical element 156G and the third optical element 156B of thelight-emitting device 100A illustrated in FIG. 12 are not provided. Inthe light-emitting device 100A illustrated in FIG. 14, the third opticalelement 156B of the light-emitting device 100A illustrated in FIG. 12 isnot provided. In the light-emitting device 100A illustrated in FIG. 15,the second optical element 156G of the light-emitting device 100Aillustrated in FIG. 12 is not provided.

With the use of a phosphorescent material emitting light in a greenwavelength range for the first light-emitting layer 110 and afluorescent material emitting light in a blue wavelength range for thesecond light-emitting layer 112, it is possible not to provide anoptical element in at least one of the regions overlapping with thesecond light-emitting element 101G and the third light-emitting element101B. With a structure in which an optical element is not provided in atleast one of the regions overlapping with the second light-emittingelement 101G and the third light-emitting element 101B, the powerconsumption of the light-emitting device 100A can be reduced. With astructure in which the third optical element 156G is not provided, powerconsumption can be reduced more effectively particularly when afluorescent material emitting light in a blue wavelength range is usedfor the third light-emitting element 101B. Note that to prevent externallight reflection, the structure illustrated in FIG. 12 in which thelight-emitting elements are all provided with the optical element ispreferred.

Structural Example 3 of Light-Emitting Device

Next, structures different from the above-described light-emittingdevices are described with reference to FIG. 16, FIG. 17, FIG. 18, FIG.19, and FIG. 20.

FIG. 16 and FIG. 18 are cross-sectional views of structures in whichtransistors are connected to the aforementioned light-emitting device100 and light-emitting device 100A, respectively. In the light-emittingdevice 100 illustrated in FIG. 16, the lower electrodes of thelight-emitting elements are each electrically connected to a transistor170. In the light-emitting device 100A illustrated in FIG. 18, the lowerelectrodes of the light-emitting elements are each electricallyconnected to the transistor 170.

The light-emitting device 100 in which each of the optical elements (thefirst optical element 156R, the second optical element 156G, and thethird optical element 156B) is provided between the transistor 170 andthe lower electrode of the light-emitting device 100 illustrated in FIG.16 is illustrated in FIG. 17. Furthermore, the light-emitting device100A in which each of the optical elements (the first optical element156R, the second optical element 156G, and the third optical element156B) is provided between the transistor 170 and the lower electrode ofthe light-emitting device 100A illustrated in FIG. 18 is illustrated inFIG. 19.

In the light-emitting device 100 illustrated in FIG. 17 or thelight-emitting device 100A illustrated in FIG. 19, light extracted fromthe lower electrodes is emitted to the substrate 102 side through theoptical elements (the first optical element 156R, the second opticalelement 156G, and the third optical element 156B). Note that thestructure illustrated in FIG. 17 or FIG. 19, in which the opticalelement or the like is not provided on the substrate 152 side, ispreferable because manufacturing cost can be reduced.

Note that the transistor 170 illustrated in FIGS. 16 to 19 is describedin detail with reference to FIG. 20. FIG. 20 is a cross-sectional viewof the transistor 170.

The transistor 170 includes a gate electrode 172 over the substrate 102,a gate insulating layer 174 over the substrate 102 and the gateelectrode 172, a semiconductor layer 176 over the gate insulating layer174, a source electrode 178 over the gate insulating layer 174 and thesemiconductor layer 176, and a drain electrode 180 over the gateinsulating layer 174 and the semiconductor layer 176. An insulatinglayer 182 is provided over the transistor 170, an insulating layer 184is provided over the insulating layer 182, and an insulating layer 186is provided over the insulating layer 184.

The insulating layer 182 is in contact with the semiconductor layer 176.The insulating layer 182 can be formed using an oxide insulatingmaterial, for example. The insulating layer 184 has a function ofsuppressing entry of impurities into the transistor 170. The insulatinglayer 184 can be formed using a nitride insulating material, forexample. The insulating layer 186 has a function of planarizingunevenness and the like due to the transistor 170 and the like. Theinsulating layer 186 can be formed using an organic resin insulatingmaterial, for example.

An opening is formed in the insulating layer 182, the insulating layer184, and the insulating layer 186. The drain electrode 180 of thetransistor 170 and the lower electrode (here, a first lower electrode104G) are electrically connected to each other through the opening.Current or voltage flowing through the lower electrode can be controlledby driving the transistor 170.

Here, each component of the aforementioned light-emitting device 100 andlight-emitting device 100A is described below in detail.

[Substrate]

The substrate 102 is used as a support of the light-emitting elements.The substrate 152 is used as a support of the optical elements. For thesubstrate 102 and 152, glass, quartz, plastic, or the like can be used,for example. Alternatively, flexible substrates can be used. Theflexible substrate is a substrate that can be bent, for example, aplastic substrate made of a polycarbonate, a polyarylate, or apolyethersulfone, and the like. A film (made of polypropylene, apolyester, poly(vinyl fluoride), poly(vinyl chloride), or the like), aninorganic vapor-deposited film, or the like can be used. Anothermaterial may be used as long as the substrate functions as a support ina manufacturing process of the light-emitting elements or the opticalelement.

The light-emitting elements and the optical element can be formed usinga variety of substrates, for example. The type of substrate is notlimited to a particular type. As the substrate, a semiconductorsubstrate (e.g., a single crystal substrate or a silicon substrate), anSOI substrate, a glass substrate, a quartz substrate, a plasticsubstrate, a metal substrate, a stainless steel substrate, a substrateincluding stainless steel foil, a tungsten substrate, a substrateincluding tungsten foil, a flexible substrate, an attachment film, paperincluding a fibrous material, a base material film, or the like can beused, for example. Examples of the glass substrate include a bariumborosilicate glass substrate, an aluminoborosilicate glass substrate, asoda lime glass substrate, and the like. Examples of the flexiblesubstrate, the attachment film, the base film, and the like aresubstrates of plastics typified by polyethylene terephthalate (PET),polyethylene naphthalate (PEN), polyether sulfone (PES), andpolytetrafluoroethylene (PTFE). Another example is a resin such asacrylic. Other examples are polypropylene, polyester, polyvinylfluoride, polyvinyl chloride, and the like. Other examples arepolyamide, polyimide, aramid, epoxy, an inorganic film formed byevaporation, paper, and the like.

Alternatively, a flexible substrate may be used as the substrate, andthe light-emitting elements and the optical element may be provideddirectly on the flexible substrate. Alternatively, a separation layermay be provided between the substrate and the light-emitting element.Alternatively, a separation layer may be provided between the substrateand the optical element. The separation layer can be used when part orthe whole of the light-emitting elements and the optical element formedover the separation layer is completed, separated from the substrate,and transferred to another substrate. In such a case, the light-emittingelements and the optical element can be transferred to a substratehaving low heat resistance or a flexible substrate as well. For theabove-described separation layer, a stack including inorganic films,which are a tungsten film and a silicon oxide film, or an organic resinfilm of polyimide or the like formed over a substrate can be used, forexample.

In other words, after the light-emitting elements and the opticalelement is formed using a substrate, the light-emitting elements and theoptical element may be transferred to another substrate. Examples of asubstrate to which the light-emitting elements and the optical elementare transferred include, in addition to the above-described substrates,a paper substrate, a cellophane substrate, an aramid film substrate, apolyimide substrate, a stone substrate, a wood substrate, a clothsubstrate (including a natural fiber (e.g., silk, cotton, or hemp), asynthetic fiber (e.g., nylon, polyurethane, or polyester), a regeneratedfiber (e.g., acetate, cupra, rayon, or regenerated polyester), or thelike), a leather substrate, and a rubber substrate. By using such asubstrate, a light-emitting element and optical element with highdurability, a light-emitting element and optical element with high heatresistance, a lightweight light-emitting element and optical element, ora thin light-emitting element and optical element can be obtained.

[Lower Electrode]

The lower electrodes (the first lower electrode 104R, the second lowerelectrode 104G, and the third lower electrode 104B) each function as ananode or a cathode of each light-emitting element. Note that each lowerelectrode is preferably formed using a reflective conductive material.As the conductive material, a conductive material having a visible-lightreflectance higher than or equal to 40% and lower than or equal to 100%,preferably higher than or equal to 70% and lower than or equal to 100%,and a resistivity lower than or equal to 1×10⁻² Ωcm can be used.Specifically, as the lower electrode, silver, aluminum, an alloycontaining silver or aluminum, or the like can be used. As the alloycontaining aluminum, an alloy containing aluminum, nickel, and lanthanumcan be used, for example. As the alloy containing silver, an alloycontaining silver, palladium, and copper can be used, for example. Thelower electrode can be formed by a sputtering method, an evaporationmethod, a printing method, a coating method, or the like.

[Transparent Conductive Layer]

The transparent conductive layers (the first transparent conductivelayer 106R, the second transparent conductive layer 106G, and the thirdtransparent conductive layer 106B) each function as part of the lowerelectrode of each light-emitting element, or the anode or the cathode ofeach light-emitting element. Furthermore, the transparent conductivelayer is used to adjust the optical path length between the lowerelectrode and the upper electrode in accordance with the desired lightwavelength so as to produce resonance of the desired light emitted fromthe light-emitting layer and increase the intensity of the light of thewavelength. For example, the thickness of the transparent conductivelayer is adjusted so that the optical path length between the electrodescan be mλ/2 (m is a natural number), where λ is the wavelength ofdesired light.

As the transparent conductive layers (the first transparent conductivelayer 106R, the second transparent conductive layer 106G, and the thirdtransparent conductive layer 106B), for example, indium oxide-tin oxide(indium tin oxide (hereinafter referred to as ITO)), indium oxide-tinoxide containing silicon or silicon oxide, indium oxide-zinc oxide(indium zinc oxide), indium oxide containing tungsten oxide and zincoxide, or the like can be used. In particular, a material with a highwork function (4.0 eV or more) is preferably used as the transparentconductive layer. The transparent conductive layer can be formed by asputtering method, an evaporation method, a printing method, a coatingmethod, or the like.

[Upper Electrode]

The upper electrode 114 functions as an anode or a cathode in each ofthe light-emitting elements. The upper electrode 114 is preferablyformed using a reflective conductive material and a light-transmittingconductive material. As the conductive material, a conductive materialhaving a visible-light reflectance higher than or equal to 20% and lowerthan or equal to 80%, preferably higher than or equal to 40% and lowerthan or equal to 70%, and a resistivity lower than or equal to 1×10⁻²Ωcm can be used. The upper electrode 114 can be formed using one or morekinds of conductive metals, alloys, conductive compounds, and the like.In particular, it is preferable to use a material with a small workfunction (3.8 eV or less). For example, aluminum, silver, an elementbelonging to Group 1 or 2 of the periodic table (e.g., an alkali metalsuch as lithium or cesium, an alkaline earth metal such as calcium orstrontium, or magnesium), an alloy containing any of these elements(e.g., Mg—Ag or Al—Li), a rare earth metal such as europium orytterbium, an alloy containing any of these rare earth metals, or thelike can be used. The upper electrode 114 can be formed by a sputteringmethod, an evaporation method, a printing method, a coating method, orthe like.

In addition, a bottom-emission light-emitting device can be obtained byinterchanging the materials used for the lower electrode and the upperelectrode with each other. In the case of the bottom-emissionlight-emitting device, the lower electrode is formed using a reflectiveconductive material and a light-transmitting conductive material, andthe upper electrode is formed using a reflective conductive material.FIG. 21 and FIG. 22 illustrate examples of the bottom-emissionlight-emitting device. FIG. 21 is a cross-sectional view in the casewhere the light-emitting device 100 illustrated in FIG. 5 is abottom-emission light-emitting device. FIG. 22 is a cross-sectional viewin the case where the light-emitting device 100A illustrated in FIG. 12is a bottom-emission light-emitting device. In the bottom-emissionlight-emitting device, the substrate 152 provided with the first opticalelement 156R, the second optical element 156G, and the third opticalelement 156B is arranged on the side where light is emitted from thelight-emitting elements, as illustrated in FIG. 21 and FIG. 22.

[Partition Wall]

The partition 136 has an insulating property and is formed using aninorganic or organic material. Examples of the inorganic materialinclude a silicon oxide film, a silicon oxynitride film, a siliconnitride oxide film, a silicon nitride film, an aluminum oxide film, andan aluminum nitride film. Examples of the organic material includephotosensitive resin materials such as an acrylic resin and a polyimideresin.

[Light-Emitting Layer]

The first light-emitting layer 110 includes a phosphorescent materialhaving a spectrum peak in the range higher than or equal to 480 nm andlower than or equal to 600 nm, and the second light-emitting layer 112includes a fluorescent material having a spectrum peak in the rangehigher than or equal to 400 nm and lower than 480 nm. The firstlight-emitting layer 110 includes either or both of anelectron-transport material and a hole-transport material in addition tothe phosphorescent material. The second light-emitting layer 112includes either or both of an electron-transport material and ahole-transport material in addition to the fluorescent material.

As the phosphorescent material, a light-emitting substance that convertstriplet excitation energy into light emission can be used. As thefluorescent material, a light-emitting substance that converts singletexcitation energy into light emission can be used. Examples of thelight-emitting substances are described below.

In the case where a phosphorescent material is used for the firstlight-emitting layer 110, examples of the light-emitting substancehaving an emission peak at 480 nm to 600 nm include organometalliciridium complexes having pyrimidine skeletons, such astris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation:Ir(mppm)₃), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III)(abbreviation: Ir(tBuppm)₃),(acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III)(abbreviation: Ir(mppm)₂(acac)),(acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III)(abbreviation: Ir(tBuppm)₂(acac)),(acetylacetonato)bis[4-(2-norbornyl)-6-phenylpyrimidinato]iridium(III)(endo- and exo-mixture) (abbreviation: Ir(nbppm)₂(acac)),(acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III)(abbreviation: Ir(tBuppm)₂(acac)), and(acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III)(abbreviation: Ir(dppm)₂(acac)); organometallic iridium complexes havingpyrazine skeletons, such as(acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(M)(abbreviation: Ir(mppr-Me)₂(acac)) and(acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III)(abbreviation: Ir(mppr-iPr)₂(acac)); organometallic iridium complexeshaving pyridine skeletons, such astris(2-phenylpyridinato-N,C^(2′))iridium(III) (abbreviation: Ir(ppy)₃),bis(2-phenylpyridinato-N,C^(2′))iridium(III) acetylacetonate(abbreviation: Ir(ppy)₂acac), bis(benzo[h]quinolinato)iridium(III)acetylacetonate (abbreviation: Ir(bzq)₂(acac)),tris(benzo[h]quinolinato)iridium(III) (abbreviation: Ir(bzq)₃),tris(2-phenylquinolinato-N,C^(2′))iridium(III) (abbreviation: Ir(pq)₃),and bis(2-phenylquinolinato-N,C^(2′))iridium(III) acetylacetonate(abbreviation: Ir(pq)₂(acac)); and a rare earth metal complex such astris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation:Tb(acac)₃(Phen)). Among the materials given above, the organometalliciridium complex having a pyrimidine skeleton has distinctively highreliability and emission efficiency and is thus especially preferable.

In the case where a fluorescent material is used for the secondlight-emitting layer 112, examples of the light-emitting substancehaving an emission peak at 400 nm to 480 nm includeN,N′-bis[4-(9H-carbazol-9-yl)phenyl]-N,N′-diphenylstilbene-4,4′-diamine(abbreviation: YGA2S),4-(9H-carbazol-9-yl)-4′-(10-phenyl-9-anthryl)triphenylamine(abbreviation: YGAPA),4-(9H-carbazol-9-yl)-4′-(9,10-diphenyl-2-anthryl)triphenylamine(abbreviation: 2YGAPPA),N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine(abbreviation: PCAPA),4-(10-phenyl-9-anthryl)-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBAPA),4-[4-(10-phenyl-9-anthryl)phenyl]-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBAPBA), perylene, 2,5,8,11-tetra(tert-butyl)perylene(abbreviation: TBP),N,N′-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-N,N′-diphenylpyrene-1,6-diamine(abbreviation: 1,6FLPAPrn),N,N′-bis(3-methylphenyl)-N,N′-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), and the like.

Alternatively, a phosphorescent material may be used for the secondlight-emitting layer 112. In the case where a phosphorescent material isused for the second light-emitting layer 112, examples of thelight-emitting substance having an emission peak at 480 nm to 600 nminclude bis[2-(4′,6′-difluorophenyl)pyridinato-N,C^(2′)]iridium(III)tetrakis(1-pyrazolyl)borate (abbreviation: FIr6),bis[2-(4′,6′-difluorophenyl)pyridinato-N,C^(2′)]iridium(III) picolinate(abbreviation: FIrpic),tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III)(abbreviation: Ir(mpptz-dmp)₃),tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazolato]iridium(III)(abbreviation: [Ir(iPr5btz)₃],tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III)(abbreviation: Ir(Mptz1-mp)₃),tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III)(abbreviation: Ir(Prptz1-Me)₃),fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III)(abbreviation: Ir(iPrpmi)₃),tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III)(abbreviation: Ir(dmpimpt-Me)₃), and the like.

As the electron-transport material used for the first light-emittinglayer 110 and the second light-emitting layer 112, a π-electrondeficient heteroaromatic compound such as a nitrogen-containingheteroaromatic compound is preferable. As the electron-transportmaterial, a π-electron deficient heteroaromatic compound, a metalcomplex, or the like can be used. Specific examples include a metalcomplex such as bis(10-hydroxybenzo[h]quinolinato)beryllium(II)(abbreviation: BeBq₂),bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III)(abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Znq),bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO), andbis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ); aheterocyclic compound having a polyazole skeleton such as2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation:PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole(abbreviation: TAZ),1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene(abbreviation: OXD-7),9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation:CO11), 2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole)(abbreviation: TPBI), and2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole(abbreviation: mDBTBIm-II); a heterocyclic compound having a diazineskeleton such as2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation:2mDBTPDBq-II),2-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline(abbreviation: 2mDBTBPDBq-II),2-[3′-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline(abbreviation: 2mCzBPDBq), 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine(abbreviation: 4,6mPnP2Pm), and4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation:4,6mDBTP2Pm-II); a heterocyclic compound having a triazine skeleton suchas2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn); and a heterocyclic compound having apyridine skeleton such as 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine(abbreviation: 35DCzPPy) and 1,3,5-tri[3-(3-pyridyl)phenyl]benzene(abbreviation: TmPyPB). Among the above-described materials,heterocyclic compounds having diazine skeletons and triazine skeletonsand heterocyclic compounds having pyridine skeletons have highreliability and are thus preferable. Heterocyclic compounds havingdiazine (pyrimidine or pyrazine) skeletons and triazine skeletons have ahigh electron-transport property and contribute to a decrease in drivevoltage.

As the hole-transport material used for the first light-emitting layer110 and the second light-emitting layer 112, a π-electron deficientheteroaromatic compound or an aromatic amine compound is preferable. Aπ-electron deficient heteroaromatic compound, an aromatic aminecompound, or the like can be preferably used. Specific examples includea compound having an aromatic amine skeleton such as2-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]spiro-9,9′-bifluorene(abbreviation: PCASF), 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl(abbreviation: NPB),N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine(abbreviation: TPD),4,4′-bis[N-(spiro-9,9′-bifluoren-2-yl)-N-phenylamino]biphenyl(abbreviation: BSPB), 4-phenyl-4′-(9-phenylfluoren-9-yl)triphenylamine(abbreviation: BPAFLP), 4-phenyl-3′-(9-phenylfluoren-9-yl)triphenylamine(abbreviation: mBPAFLP),4-phenyl-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation:PCBA1BP), 4,4′-diphenyl-4″-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBBi1BP),4-(1-naphthyl)-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBANB),4,4′-di(1-naphthyl)-4″-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBNBB),9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine(abbreviation: PCBAF),N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9′-bifluoren-2-amine(abbreviation: PCBASF), andN-(1,1′-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF); a compound having a carbazoleskeleton such as 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP),4,4′-di(N-carbazolyl)biphenyl (abbreviation: CBP), and3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), or9-phenyl-9H-3-(9-phenyl-9H-carbazol-3-yl)carbazole (abbreviation: PCCP);a compound having a thiophene skeleton such as4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation:DBT3P-II),2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene(abbreviation: DBTFLP-III), and4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene(abbreviation: DBTFLP-IV); and a compound having a furan skeleton suchas 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation:DBF3P-II) and4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran(abbreviation: mmDBFFLBi-II). Among the above-described materials,compounds having aromatic amine skeletons and compounds having carbazoleskeletons are preferable because these compounds are highly reliable andhave high hole-transport properties to contribute to a reduction indrive voltage.

Furthermore, as the hole-transport material used for the firstlight-emitting layer 110 and the second light-emitting layer 112, a highmolecular compound such as poly(N-vinylcarbazole) (abbreviation: PVK),poly(4-vinyltriphenylamine) (abbreviation: PVTPA),poly[N-(4-{N′-[4-(4-diphenylamino)phenyl]phenyl-N′-phenylamino}phenyl)methacrylamide](abbreviation: PTPDMA), orpoly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine](abbreviation:Poly-TPD) can also be used.

[Hole-Injection Layer and Hole-Transport Layer]

The hole-injection layer 131 is a layer that injects holes into thefirst light-emitting layer 110 and the second light-emitting layer 112through the hole-transport layer 132 with a high hole-transport propertyand includes a hole-transport material and an acceptor material. When ahole-transport material and an acceptor material are included, electronsare extracted from the hole-transport material by the acceptor materialto generate holes, and the holes are injected into the firstlight-emitting layer 110 and the second light-emitting layer 112 throughthe hole-transport layer 132. Note that the hole-transport layer 132 isformed using a hole-transport material.

As a hole-transport material used for the hole-injection layer 131 andthe hole-transport layer 132, a material similar to the aforementionedhole-transport material used for the first light-emitting layer 110 andthe second light-emitting layer 112 can be used.

Examples of the acceptor material used for the hole-injection layer 131include oxide of a metal belonging to any of Group 4 to Group 8 of theperiodic table. Specifically, molybdenum oxide is particularlypreferable.

The hole-injection layer 131 and the hole-transport layer 132 may beformed using a material different between light-emitting elements orwith a different thickness in some cases.

[Electron-Transport Layer]

As an electron-transport material used for the electron-transport layer133, a material similar to the aforementioned electron-transportmaterial used for the first light-emitting layer 110 and the secondlight-emitting layer 112 can be used.

[Electron-Injection Layer]

The electron-injection layer 134 is a layer including a substance with ahigh electron-injection property. For the electron-injection layer 134,an alkali metal, an alkaline earth metal, or a compound thereof, such aslithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF₂),or lithium oxide (LiO_(x)), can be used. Alternatively, a rare earthmetal compound like erbium fluoride (ErF₃) can be used. Electrode mayalso be used for the electron-injection layer 134. Examples of theelectrode include a substance in which electrons are added at highconcentration to calcium oxide-aluminum oxide and the like.

Alternatively, the electron-injection layer 134 may be formed using acomposite material in which an organic compound and an electron donor(donor) are mixed. The composite material is superior in anelectron-injection property and an electron-transport property, becauseelectrons are generated in the organic compound by the electron donor.The organic compound here is preferably a material excellent intransporting the generated electrons; specifically, for example, thesubstances for forming the electron-transport layer 133 (e.g., a metalcomplex or a heteroaromatic compound) can be used. As the electrondonor, a substance showing an electron-donating property with respect tothe organic compound is used. Specifically, an alkali metal, an alkalineearth metal, and a rare earth metal are preferable, and lithium, cesium,magnesium, calcium, erbium, ytterbium, and the like are given.Furthermore, an alkali metal oxide or an alkaline earth metal oxide ispreferable, and for example, lithium oxide, calcium oxide, barium oxide,and the like can be given. Alternatively, Lewis base such as magnesiumoxide can also be used. An organic compound such as tetrathiafulvalene(abbreviation: TTF) can also be used.

The electron-injection layer 134 and the electron-transport layer 133may be formed using a material different between light-emitting elementsor with a different thickness in some cases.

[Optical Adjustment Layer]

The optical adjustment layer 108 is a layer having a function ofadjusting the optical path length between the lower electrode and thelight-emitting layer. For the optical adjustment layer 108, for example,a hole-transport material or an electron-transport material is used. Asthe hole-transport material, a material similar to the aforementionedhole-transport material used for the first light-emitting layer 110 andthe second light-emitting layer 112 can be used. As theelectron-transport material, a material similar to the aforementionedelectron-transport material used for the first light-emitting layer 110and the second light-emitting layer 112 can be used.

[Light-Blocking Layer]

The light-blocking layer 154 has a function of reducing the reflectionof external light. The light-blocking layer 154 has a function ofpreventing mixture of light emitted from an adjacent light-emittingelement. As the light-blocking layer 154, a metal, a resin containingblack pigment, carbon black, a metal oxide, a composite oxide containinga solid solution of a plurality of metal oxides, or the like can beused.

[Light-Emitting Element]

The first optical element 156R, the second optical element 156G, and thethird optical element 156B selectively transmit light with a particularcolor out of incident light. For example, a color filter, a band passfilter, a multilayer filter, or the like can be used. Color conversionelements can be used as the optical elements. A color conversion elementis an optical element that converts incident light into light having alonger wavelength than the incident light. As the color conversionelements, quantum-dot elements are preferably used. The usage of thequantum-dot type can increase color reproducibility of thelight-emitting device.

The first optical element 156R transmits light in a red wavelength rangeout of light emitted from the first light-emitting element 101R. Thesecond optical element 156G transmits light in a green wavelength rangeout of light emitted from the second light-emitting element 101G. Inaddition, the third optical element 156B transmits light in a bluewavelength range out of light emitted from the third light-emittingelement 101B.

Note that an optical element different from the above-described opticalelements may be provided so as to overlap with the first light-emittingelement 101R, the second light-emitting element 101G, and the thirdlight-emitting element 101B. As another optical element, for example, acircularly polarizing plate, an anti-reflective film, and the like canbe given. A circularly polarizing plate provided on the side where lightemitted from the light-emitting element of the light-emitting device isextracted can prevent a phenomenon in which light entering from theoutside of the light-emitting device is reflected inside thelight-emitting device and returned to the outside. An anti-reflectivefilm can weaken external light reflected by a surface of thelight-emitting device. Accordingly, light emitted from thelight-emitting device can be observed clearly.

<Manufacturing Method 1 of Light-Emitting Device>

Next, a manufacturing method of a light-emitting device of oneembodiment of the present invention is described below with reference toFIGS. 23A and 23B, FIGS. 24A and 24B, and FIGS. 25A and 25B. Here, amanufacturing method of the light-emitting device 100 illustrated inFIG. 5 is described.

FIGS. 23A and 23B, FIGS. 24A and 24B, and FIGS. 25A and 25B arecross-sectional views for illustrating the manufacturing method of thelight-emitting device of one embodiment of the present invention.

The manufacturing method of the light-emitting device 100 describedbelow includes first to seventh steps.

[First Step]

The first step is a step for forming the lower electrodes (the firstlower electrode 104R, the second lower electrode 104G, and the thirdlower electrode 104B) of the light-emitting elements, the transparentconductive layers (the first transparent conductive layer 106R, thesecond transparent conductive layer 106G, and the third transparentconductive layer 106B) of the light-emitting elements, and the partition136 covering end portions of the lower electrode and the transparentconductive layer of each light-emitting element (see FIG. 23A).

In the first step, since there is no possibility of damaging alight-emitting layer containing an organic compound, a variety ofmicromachining technologies can be employed. In this embodiment, areflective conductive film is formed by a sputtering method, subjectedto patterning by a photolithography technique, and then processed intoan island shape by a dry etching method to form the first lowerelectrode 104R, the second lower electrode 104G, and the third lowerelectrode 104B.

Next, a light-transmitting conductive film is formed over the firstlower electrode 104R, subjected to patterning by a photolithographytechnique, and then processed into an island shape by a wet etchingmethod to form the first transparent conductive layer 106R. After that,a light-transmitting conductive film is formed over the second lowerelectrode 104G and the third lower electrode 104B, subjected topatterning by a photolithography technique, and then processed intoisland shapes by a wet etching method to form the second transparentconductive layer 106G and the third transparent conductive layer 106B.

Then, the partition 136 is formed to cover end portions of theisland-shaped lower electrode and the island-shaped transparentconductive layer. The partition 136 includes an opening overlapping withthe lower electrode. The transparent conductive layer exposed by theopening functions as the lower electrode of the light-emitting element.

In the first step, an alloy film of silver, palladium, and copper isused as the reflective conductive film, an ITO film is used as thelight-transmitting conductive film, and an acrylic resin is used as thepartition 136.

Note that transistors may be formed over the substrate 102 before thefirst step. The transistors may be electrically connected to the lowerelectrodes (the first lower electrode 104R, the second lower electrode104G, and the third lower electrode 104B).

[Second Step]

The second step is a step for forming the hole-injection layer 131 andthe hole-transport layer 132 over the transparent conductive layers (thefirst transparent conductive layer 106R, the second transparentconductive layer 106G, and the third transparent conductive layer 106B)and the partitions 136 (see FIG. 23B).

In the second step, the hole-injection layer 131 and the hole-transportlayer 132 are formed by evaporation of an organic compound. Note thatthe hole-injection layer 131 and the hole-transport layer 132 can beshared between the light-emitting elements. Therefore, a light-emittingelement with low manufacturing cost and high productivity can beobtained.

[Third Step]

The third step is a step for forming the optical adjustment layer 108and the first light-emitting layer 110 with a shadow mask 190 (see FIG.24A).

In the third step, the shadow mask 190 having an opening 191 is providedso as to overlap the third transparent conductive layer 106B, and theoptical adjustment layer 108 and the first light-emitting layer 110 areformed by evaporation of an organic compound 192 through the shadow mask190.

In the third step, the substrate 102 is introduced into an evaporationapparatus, and the shadow mask 190 is provided on the evaporation source(not illustrated) side. Next, alignment for providing the opening 191 ofthe shadow mask 190 in a desired position is performed. Note that theshadow mask 190 is a shielding plate provided with the opening 191 andformed of foil of a metal or the like with a thickness greater than orequal to several tens of micrometers or a plate of a metal or the likewith a thickness greater than or equal to several hundreds ofmicrometers.

The optical adjustment layer 108 is formed using a hole-transportmaterial. Any of the aforementioned organic compounds can be used as thehole-transport material.

The first light-emitting layer 110 includes a light-emitting materialhaving a spectrum peak in the range of higher than or equal to 480 nmand lower than 600 nm. As the light-emitting material, a phosphorescentorganic compound emitting light in a green wavelength range can be used.The phosphorescent organic compound may be evaporated alone or thephosphorescent organic compound mixed with another material may beevaporated. For example, the phosphorescent organic compound may be usedas a guest material, and the guest material may be dispersed into a hostmaterial having higher excitation energy than the guest material andevaporated.

For example, only one step is required to form layers in selected pixelswhen the optical adjustment layer 108 and the first light-emitting layer110 are consecutively evaporated. Note that in some cases, the opticaladjustment layer 108 and the first light-emitting layer 110 may beevaporated each in different steps.

[Fourth Step]

The fourth step is a step for forming the second light-emitting layer112, the electron-transport layer 133, the electron-injection layer 134,and the upper electrode 114 over the hole-transport layer 132 and thefirst light-emitting layer 110 (see FIG. 24B).

The second light-emitting layer 112 includes a light-emitting materialhaving a spectrum peak in the range of higher than or equal to 400 nmand lower than 480 nm. As the light-emitting material, a fluorescentorganic compound emitting light in a blue wavelength range can be used.The fluorescent organic compound may be evaporated alone or thefluorescent organic compound mixed with another material may beevaporated. For example, the fluorescent organic compound may be used asa guest material, and the guest material may be dispersed into a hostmaterial having higher excitation energy than the guest material andevaporated.

In the fourth step, the second light-emitting layer 112, theelectron-transport layer 133, the electron-injection layer 134, and theupper electrode 114 are formed by evaporation of an organic compound.Note that the second light-emitting layer 112, the electron-transportlayer 133, the electron-injection layer 134, and the upper electrode 114can be shared between the light-emitting elements. Therefore, alight-emitting element with low manufacturing cost and high productivitycan be obtained.

Through the above-described steps, the first light-emitting element101R, the second light-emitting element 101G, and the thirdlight-emitting element 101B are formed over the substrate 102.

[Fifth Step]

The fifth step is a step for forming the light-blocking layer 154 overthe substrate 152 (see FIG. 25A).

In the fifth step, as the light-blocking layer 154, an organic resinfilm containing black pigment is formed in a desired region.

[Sixth Step]

The sixth step is a step for forming the first optical element 156R, thesecond optical element 156G, and the third optical element 156B over thesubstrate 152 and the light-blocking layer 154 (see FIG. 25B).

In the sixth step, as the first optical element 156R, an organic resinfilm containing red pigment is formed in a desired region. As the secondoptical element 156G, an organic resin film containing green pigment isformed in a desired region. As the third optical element 156B, anorganic resin film containing blue pigment is formed in a desiredregion.

[Seventh Step]

The seventh step is a step for attaching the first light-emittingelement 101R, the second light-emitting element 101G, and the thirdlight-emitting element 101B formed over the substrate 102 to thelight-blocking layer 154, the first optical element 156R, the secondoptical element 156G, and the third optical element 156B formed over thesubstrate 152 and performing sealing with a sealant (not illustrated).

Through the above-described steps, the light-emitting device 100illustrated in FIG. 5 can be formed. In this embodiment, inmanufacturing the light-emitting elements, only one step (the step fordepositing the optical adjustment layer 108 and the first light-emittinglayer 110) is required to form layers in selected pixels; thus, amanufacturing method of a light-emitting device with high productivitycan be provided. Consequently, a manufacturing method of a novellight-emitting device in which a decrease in aperture ratio accompaniedby fabrication of a high-definition device is suppressed can beprovided. Furthermore, a novel light-emitting device which can beproduced easily can be provided.

<Manufacturing Method 2 of Light-Emitting Device>

Next, a manufacturing method of a light-emitting device of oneembodiment of the present invention is described below with reference toFIGS. 26A and 26B, FIGS. 27A and 27B, and FIGS. 28A and 28B. Here, amanufacturing method of the light-emitting device 100A illustrated inFIG. 12 is described.

FIGS. 26A and 26B, FIGS. 27A and 27B, and FIGS. 28A and 28B arecross-sectional views for illustrating the manufacturing method of thelight-emitting device of one embodiment of the present invention.

The manufacturing method of the light-emitting device 100A describedbelow includes first to seventh steps.

[First Step]

The first step is a step for forming the lower electrodes (the firstlower electrode 104R, the second lower electrode 104G, and the thirdlower electrode 104B) of the light-emitting elements, the transparentconductive layers (the first transparent conductive layer 106R, thesecond transparent conductive layer 106G, and the third transparentconductive layer 106B) of the light-emitting elements, and the partition136 covering end portions of the lower electrode and the transparentconductive layer of each light-emitting element (see FIG. 26A).

In the first step, since there is no possibility of damaging alight-emitting layer containing an organic compound, a variety ofmicromachining technologies can be employed. In this embodiment, areflective conductive film is formed by a sputtering method, subjectedto patterning by a photolithography technique, and then processed intoan island shape by a dry etching method to form the first lowerelectrode 104R, the second lower electrode 104G, and the third lowerelectrode 104B.

Next, a light-transmitting conductive film is formed over the firstlower electrode 104R, subjected to patterning by a photolithographytechnique, and then processed into an island shape by a wet etchingmethod to form the first transparent conductive layer 106R. After that,a light-transmitting conductive film is formed over the second lowerelectrode 104G and the third lower electrode 104B, subjected topatterning by a photolithography technique, and then processed intoisland shapes by a wet etching method to form the second transparentconductive layer 106G and the third transparent conductive layer 106B.

Then, the partition 136 is formed to cover end portions of theisland-shaped lower electrode and the island-shaped transparentconductive layer. The partition 136 includes an opening overlapping withthe lower electrode. The transparent conductive layer exposed by theopening functions as the lower electrode of the light-emitting element.

In the first step, an alloy film of silver, palladium, and copper isused as the reflective conductive film, an ITO film is used as thelight-transmitting conductive film, and an acrylic resin is used as thepartition 136.

Note that transistors may be formed over the substrate 102 before thefirst step. The transistors may be electrically connected to the lowerelectrodes (the first lower electrode 104R, the second lower electrode104G, and the third lower electrode 104B).

[Second Step]

The second step is a step for forming the electron-injection layer 134and the electron-transport layer 133 over the transparent conductivelayers (the first transparent conductive layer 106R, the secondtransparent conductive layer 106G, and the third transparent conductivelayer 106B) and the partitions 136 (see FIG. 26B).

In the second step, the electron-injection layer 134 and theelectron-transport layer 133 are formed by evaporation of an organiccompound. Note that the electron-injection layer 134 and theelectron-transport layer 133 can be shared between the light-emittingelements. Therefore, a light-emitting element with low manufacturingcost and high productivity can be obtained.

[Third Step]

The third step is a step for forming the optical adjustment layer 108and the first light-emitting layer 110 with the shadow mask 190 (seeFIG. 27A).

In the third step, the shadow mask 190 having the opening 191 isprovided so as to overlap the third transparent conductive layer 106B,and the optical adjustment layer 108 and the first light-emitting layer110 are formed by evaporation of the organic compound 192 through theshadow mask 190.

In the third step, the substrate 102 is introduced into an evaporationapparatus, and the shadow mask 190 is provided on the evaporation source(not illustrated) side. Next, alignment for providing the opening 191 ofthe shadow mask 190 in a desired position is performed. Note that theshadow mask 190 is a shielding plate provided with the opening 191 andformed of foil of a metal or the like with a thickness greater than orequal to several tens of micrometers or a plate of a metal or the likewith a thickness greater than or equal to several hundreds ofmicrometers.

The optical adjustment layer 108 is formed using an electron-transportmaterial. Any of the aforementioned organic compounds can be used as theelectron-transport material.

The first light-emitting layer 110 includes a light-emitting materialhaving a spectrum peak in the range of higher than or equal to 480 nmand lower than 600 nm. As the light-emitting material, a phosphorescentorganic compound emitting light in a green wavelength range can be used.The phosphorescent organic compound may be evaporated alone or thephosphorescent organic compound mixed with another material may beevaporated. For example, the phosphorescent organic compound may be usedas a guest material, and the guest material may be dispersed into a hostmaterial having higher excitation energy than the guest material andevaporated.

For example, only one step is required to form layers in selected pixelswhen the optical adjustment layer 108 and the first light-emitting layer110 are consecutively evaporated. Note that in some cases, the opticaladjustment layer 108 and the first light-emitting layer 110 may beevaporated each in different steps.

[Fourth Step]

The fourth step is a step for forming the second light-emitting layer112, the hole-transport layer 132, the electron-injection layer 131, andthe upper electrode 114 over the electron-transport layer 133 and thefirst light-emitting layer 110 (see FIG. 27B).

The second light-emitting layer 112 includes a light-emitting materialhaving a spectrum peak in the range of higher than or equal to 400 nmand lower than 480 nm. As the light-emitting material, a fluorescentorganic compound emitting light in a blue wavelength range can be used.The fluorescent organic compound may be evaporated alone or thefluorescent organic compound mixed with another material may beevaporated. For example, the fluorescent organic compound may be used asa guest material, and the guest material may be dispersed into a hostmaterial having higher excitation energy than the guest material andevaporated.

In the fourth step, the second light-emitting layer 112, thehole-transport layer 132, the hole-injection layer 131, and the upperelectrode 114 are formed by evaporation of an organic compound. Notethat the second light-emitting layer 112, the hole-transport layer 132,the hole-injection layer 131, and the upper electrode 114 can be sharedbetween the light-emitting elements. Therefore, a light-emitting elementwith low manufacturing cost and high productivity can be obtained.

Through the above-described steps, the first light-emitting element101R, the second light-emitting element 101G, and the thirdlight-emitting element 101B are formed over the substrate 102.

[Fifth Step]

The fifth step is a step for forming the light-blocking layer 154 overthe substrate 152 (see FIG. 28A).

In the fifth step, as the light-blocking layer 154, an organic resinfilm containing black pigment is formed in a desired region.

[Sixth Step]

The sixth step is a step for forming the first optical element 156R, thesecond optical element 156G, and the third optical element 156B over thesubstrate 152 and the light-blocking layer 154 (see FIG. 28B).

In the sixth step, as the first optical element 156R, an organic resinfilm containing red pigment is formed in a desired region. As the secondoptical element 156G, an organic resin film containing green pigment isformed in a desired region. As the third optical element 156B, anorganic resin film containing blue pigment is formed in a desiredregion.

[Seventh Step]

The seventh step is a step for attaching the first light-emittingelement 101R, the second light-emitting element 101G, and the thirdlight-emitting element 101B formed over the substrate 102 to thelight-blocking layer 154, the first optical element 156R, the secondoptical element 156G, and the third optical element 156B formed over thesubstrate 152 and performing sealing with a sealant (not illustrated).

Through the above-described steps, the light-emitting device 100Aillustrated in FIG. 12 can be formed. In this embodiment, inmanufacturing the light-emitting elements, only one step (the step fordepositing the optical adjustment layer 108 and the first light-emittinglayer 110) is required to form layers in selected pixels; thus, amanufacturing method of a light-emitting device with high productivitycan be provided. Consequently, a manufacturing method of a novellight-emitting device in which a decrease in aperture ratio accompaniedby fabrication of a high-definition device is suppressed can beprovided. Furthermore, a novel light-emitting device which can beproduced easily can be provided.

The structure described in this embodiment can be combined with any ofthe structures described in the other embodiments and examples asappropriate.

Embodiment 2

In this embodiment, a light-emitting device of one embodiment of thepresent invention, which is a different mode from the light-emittingdevice in Embodiment 1, will be described below with reference to FIGS.29A and 29B, FIGS. 30A and 30B, FIG. 31, FIG. 32, FIG. 33, and FIG. 34.Note that common reference numerals are used for components that havefunctions similar to functions described in Embodiment 1, and detaileddescriptions of the components are omitted in some cases.

Structural Example 4 of Light-Emitting Device

FIGS. 29A and 29B, FIGS. 30A and 30B, and FIG. 31 are cross-sectionalviews each illustrating an example of the light-emitting device ofembodiment of the present invention. Plan views of the light-emittingdevices of FIGS. 29A and 29B and FIGS. 30A and 30B are not shown herebecause they are similar to the plan view of the light-emitting device100 illustrated in FIG. 1A, and a plan view of the light-emitting deviceof FIG. 31 is not shown here because it is similar to the plan view ofthe light-emitting device 100 illustrated in FIG. 4.

A light-emitting device 150 illustrated in FIG. 29A includes a firstlight-emitting element 1518, a second light-emitting element 151G, andthe third light-emitting element 101B. The first light-emitting element151R includes the first lower electrode 104R, the first transparentconductive layer 106R over the first lower electrode 104R, the secondlight-emitting layer 112 over the first transparent conductive layer106R, the first light-emitting layer 110 over the second light-emittinglayer 112, and the upper electrode 114 over the first light-emittinglayer 110. The second light-emitting element 151G includes the secondlower electrode 104G, the second transparent conductive layer 106G overthe second lower electrode 104G, the second light-emitting layer 112over the second transparent conductive layer 106G, the firstlight-emitting layer 110 over the second light-emitting layer 112, andthe upper electrode 114 over the first light-emitting layer 110. Thethird light-emitting element 101B includes the third lower electrode104B, the third transparent conductive layer 106B over the third lowerelectrode 104B, the second light-emitting layer 112 over the thirdtransparent conductive layer 106B, and the upper electrode 114 over thesecond light-emitting layer 112.

The light-emitting device 150 illustrated in FIG. 29B includes the firstlight-emitting element 151R, the second light-emitting element 151G, andthe third light-emitting element 101B. The first light-emitting element151R includes the first lower electrode 104R, the first transparentconductive layer 106R over the first lower electrode 104R, thehole-injection layer 131 over the first transparent conductive layer106R, the hole-transport layer 132 over the hole-injection layer 131,the second light-emitting layer 112 over the hole-transport layer 132,the first light-emitting layer 110 over the second light-emitting layer112, the electron-transport layer 133 over the first light-emittinglayer 110, the electron-injection layer 134 over the electron-transportlayer 133, and the upper electrode 114 over the electron-injection layer134. The second light-emitting element 151G includes the second lowerelectrode 104G, the second transparent conductive layer 106G over thesecond lower electrode 104G, the hole-injection layer 131 over thesecond transparent conductive layer 106G, the hole-transport layer 132over the hole-injection layer 131, the second light-emitting layer 112over the hole-transport layer 132, the first light-emitting layer 110over the second light-emitting layer 112, the electron-transport layer133 over the first light-emitting layer 110, the electron-injectionlayer 134 over the electron-transport layer 133, and the upper electrode114 over the electron-injection layer 134. The third light-emittingelement 101B includes the third lower electrode 104B, the thirdtransparent conductive layer 106B over the third lower electrode 104B,the hole-injection layer 131 over the third transparent conductive layer106B, the hole-transport layer 132 over the hole-injection layer 131,the second light-emitting layer 112 over the hole-transport layer 132,the electron-transport layer 133 over the second light-emitting layer112, the electron-injection layer 134 over the electron-transport layer133, and the upper electrode 114 over the electron-injection layer 134.

That is, the light-emitting devices 150 illustrated in FIGS. 29A and 29Beach include the first light-emitting element 151R instead of the firstlight-emitting element 101R of the light-emitting device 100 and thesecond light-emitting element 151G instead of the second light-emittingelement 101G of the light-emitting device 100. In the firstlight-emitting element 151R, the stacking order of the light-emittinglayers is different from that in the first light-emitting element 101R.In the second light-emitting element 151G, the stacking order of thelight-emitting layers is different from that in the secondlight-emitting element 101G. Specifically, the first light-emittinglayer 110 is provided over the second light-emitting layer 112 in eachof the first light-emitting element 151R and the second light-emittingelement 151G.

In the light-emitting device 150 illustrated in FIG. 30A, the opticaladjustment layer 108 is provided in addition to the components of thelight-emitting device 150 illustrated in FIG. 29A. Specifically, thefirst light-emitting element 151R includes the optical adjustment layer108 between the first light-emitting layer 110 and the upper electrode114. The second light-emitting element 151G includes the opticaladjustment layer 108 between the first light-emitting layer 110 and theupper electrode 114.

In the light-emitting device 150 illustrated in FIG. 30B, the opticaladjustment layer 108 is provided in addition to the components of thelight-emitting device 150 illustrated in FIG. 29B. Specifically, thefirst light-emitting element 151R includes the optical adjustment layer108 between the first light-emitting layer 110 and theelectron-transport layer 133. The second light-emitting element 151Gincludes the optical adjustment layer 108 between the firstlight-emitting layer 110 and the electron-transport layer 133.

As illustrated in FIGS. 30A and 30B, with the structure provided withthe optical adjustment layer 108, an optical path length between each ofthe lower electrodes (the first lower electrode 104R and the secondlower electrode 104G) and the upper electrode 114 can be adjusted. Ineach of the light-emitting devices 150 illustrated in FIGS. 30A and 30B,the optical adjustment layer 108 is provided over the firstlight-emitting layer 110.

The light-emitting device 150 illustrated in FIG. 31 includes thepartition 136 and the substrate 152 in addition to the components of thelight-emitting device 150 illustrated in FIG. 30B. The partitions 136are provided at outer portions of the light-emitting elements and have afunction of covering the end portions of either or both of the lowerelectrodes and the transparent conductive layers of the light-emittingelements. The substrate 152 is provided with the light-blocking layer154, the first optical element 156R, the second optical element 156G,and the third optical element 156B. The light-blocking layer 154 isprovided to overlap with the partition 136. The first optical element156R, the second optical element 156G, and the third optical element156B are provided to overlap with the first light-emitting element 151R,the second light-emitting element 151G, and the third light-emittingelement 101B, respectively.

As described above, the light-emitting device 150 is different from thelight-emitting device 100 in the stacking order of the firstlight-emitting layer 110, the second light-emitting layer 112, and theoptical adjustment layer 108. Since the stacking order of the firstlight-emitting layer 110, the second light-emitting layer 112, and theoptical adjustment layer 108 is changed, it is necessary to consider thecarrier balance with the materials in the layers. For example, thesecond light-emitting layer 112 is formed using a material with ahole-transport property higher than that of the material used for thefirst light-emitting layer 110, and the optical adjustment layer 108 isformed using an electron-transport material.

With the above-described structures, in the first light-emitting element151R and the second light-emitting element 151G, the secondlight-emitting layer 112 does not contribute to light emission. Forexample, for the second light-emitting layer 112, a material with a highhole-transport property and a low electron-transport property or amaterial having a lower HOMO level than the material used for the firstlight-emitting layer 110 is used.

The other structures are similar to those of the light-emitting device100 described in Embodiment 1 and have similar effects. Theabove-described structures of the light-emitting devices can be combinedas appropriate.

Structural Example 5 of Light-Emitting Device

FIG. 32, FIG. 33, and FIG. 34 are cross-sectional views eachillustrating an example of the light-emitting device of embodiment ofthe present invention. Plan views of the light-emitting devices of FIG.32 and FIG. 33 are not shown here because they are similar to the planview of the light-emitting device 100 illustrated in FIG. 1A, and a planview of the light-emitting device of FIG. 34 is not shown here becauseit is similar to the plan view of the light-emitting device 100illustrated in FIG. 4.

A light-emitting device 150A illustrated in FIG. 32 includes the firstlight-emitting element 151R, the second light-emitting element 151G, andthe third light-emitting element 101B. The first light-emitting element151R includes the first lower electrode 104R, the first transparentconductive layer 106R over the first lower electrode 104R, theelectron-injection layer 134 over the first transparent conductive layer106R, the electron-transport layer 133 over the electron-injection layer134, the second light-emitting layer 112 over the electron-transportlayer 133, the first light-emitting layer 110 over the secondlight-emitting layer 112, the hole-transport layer 132 over the firstlight-emitting layer 110, the hole-injection layer 131 over thehole-transport layer 132, and the upper electrode 114 over thehole-injection layer 131. The second light-emitting element 151Gincludes the second lower electrode 104G, the second transparentconductive layer 106G over the second lower electrode 104G, theelectron-injection layer 134 over the second transparent conductivelayer 106G, the electron-transport layer 133 over the electron-injectionlayer 134, the second light-emitting layer 112 over theelectron-transport layer 133, the first light-emitting layer 110 overthe second light-emitting layer 112, the hole-transport layer 132 overthe first light-emitting layer 110, the hole-injection layer 131 overthe hole-transport layer 132, and the upper electrode 114 over thehole-injection layer 131. The third light-emitting element 101B includesthe third lower electrode 104B, the third transparent conductive layer106B over the third lower electrode 104B, the electron-injection layer134 over the third transparent conductive layer 106B, theelectron-transport layer 133 over the electron-injection layer 134, thesecond light-emitting layer 112 over the electron-transport layer 133,the hole-transport layer 132 over the second light-emitting layer 112,the hole-injection layer 131 over the hole-transport layer 132, and theupper electrode 114 over the hole-injection layer 131.

That is, the light-emitting device 150A illustrated in FIG. 32 includesthe first light-emitting element 151R instead of the firstlight-emitting element 101R of the light-emitting device 100A and thesecond light-emitting element 151G instead of the second light-emittingelement 101G of the light-emitting device 100A. In the firstlight-emitting element 151R, the stacking order of the light-emittinglayers is different from that in the first light-emitting element 101R.In the second light-emitting element 151G, the stacking order of thelight-emitting layers is different from that in the secondlight-emitting element 101G. Specifically, the first light-emittinglayer 110 is provided over the second light-emitting layer 112 in eachof the first light-emitting element 151R and the second light-emittingelement 151G.

In the light-emitting device 150A illustrated in FIG. 33, the opticaladjustment layer 108 is provided in addition to the components of thelight-emitting device 150A illustrated in FIG. 32. Specifically, thefirst light-emitting element 151R includes the optical adjustment layer108 between the first light-emitting layer 110 and the hole-transportlayer 132. The second light-emitting element 151G includes the opticaladjustment layer 108 between the first light-emitting layer 110 and thehole-transport layer 132.

As illustrated in FIG. 33, with the structure provided with the opticaladjustment layer 108, an optical path length between each of the lowerelectrodes (the first lower electrode 104R and the second lowerelectrode 104G) and the upper electrode 114 can be adjusted. In thelight-emitting device 150A illustrated in FIG. 33, the opticaladjustment layer 108 is provided over the first light-emitting layer110.

The light-emitting device 150A illustrated in FIG. 34 includes thepartition 136 and the substrate 152 in addition to the components of thelight-emitting device 150A illustrated in FIG. 33. The partitions 136are provided at outer portions of the light-emitting elements and have afunction of covering the end portions of either or both of the lowerelectrodes and the transparent conductive layers of the light-emittingelements. The substrate 152 is provided with the light-blocking layer154, the first optical element 156R, the second optical element 156G,and the third optical element 156B. The light-blocking layer 154 isprovided to overlap with the partition 136. The first optical element156R, the second optical element 156G, and the third optical element156B are provided to overlap with the first light-emitting element 151R,the second light-emitting element 151G, and the third light-emittingelement 101B, respectively.

As described above, the light-emitting device 150A is different from thelight-emitting device 100 in the stacking order of the firstlight-emitting layer 110, the second light-emitting layer 112, and theoptical adjustment layer 108. Since the stacking order of the firstlight-emitting layer 110, the second light-emitting layer 112, and theoptical adjustment layer 108 is changed, it is necessary to consider thecarrier balance with the materials in the layers. For example, thesecond light-emitting layer 112 is formed using a material with anelectron-transport property higher than that of the material used forthe first light-emitting layer 110, and the optical adjustment layer 108is formed using a hole-transport material.

With the above structures, in the first light-emitting element 151R andthe second light-emitting element 151G, the second light-emitting layer112 does not contribute to light emission. For example, for the secondlight-emitting layer 112, a material with a high electron-transportproperty and a low hole-transport property or a material having a lowerHOMO level than the material used for the first light-emitting layer 110is used.

The other structures are similar to those of the light-emitting device100A described in Embodiment 1 and have similar effects. Theabove-described structures of the light-emitting devices can be combinedas appropriate.

The structure described in this embodiment can be combined with any ofthe structures described in the other embodiments and examples asappropriate.

Embodiment 3

In this embodiment, a display device including a light-emitting deviceof one embodiment of the present invention will be described withreference to FIGS. 35A and 35B.

FIG. 35A is a block diagram illustrating the display device of oneembodiment of the present invention, and FIG. 35B is a circuit diagramillustrating a pixel circuit of the display device of one embodiment ofthe present invention.

The display device illustrated in FIG. 35A includes a region includingpixels of display elements (the region is hereinafter referred to as apixel portion 802), a circuit portion provided outside the pixel portion802 and including circuits for driving the pixels (the portion ishereinafter referred to as a driver circuit portion 804), circuitshaving a function of protecting elements (the circuits are hereinafterreferred to as protection circuits 806), and a terminal portion 807.Note that the protection circuits 806 are not necessarily provided.

Part or the whole of the driver circuit portion 804 is preferably formedover a substrate over which the pixel portion 802 is formed, in whichcase the number of components and the number of terminals can bereduced. When part or the whole of the driver circuit portion 804 is notformed over the substrate over which the pixel portion 802 is formed,the part or the whole of the driver circuit portion 804 can be mountedby chip-on-glass (COG) or tape automated bonding (TAB).

The pixel portion 802 includes a plurality of circuits for drivingdisplay elements arranged in X rows (X is a natural number of 2 or more)and Y columns (Y is a natural number of 2 or more) (such circuits arehereinafter referred to as pixel circuits 801). The driver circuitportion 804 includes driver circuits such as a circuit for supplying asignal (scan signal) to select a pixel (the circuit is hereinafterreferred to as a gate driver 804 a) and a circuit for supplying a signal(data signal) to drive a display element in a pixel (the circuit ishereinafter referred to as a source driver 804 b).

The gate driver 804 a includes a shift register or the like. Through theterminal portion 807, the gate driver 804 a receives a signal fordriving the shift register and outputs a signal. For example, the gatedriver 804 a receives a start pulse signal, a clock signal, or the likeand outputs a pulse signal. The gate driver 804 a has a function ofcontrolling the potentials of wirings supplied with scan signals (suchwirings are hereinafter referred to as scan lines GL_1 to GL_X). Notethat a plurality of gate drivers 804 a may be provided to control thescan lines GL_1 to GL_X separately. Alternatively, the gate driver 804 ahas a function of supplying an initialization signal. Without beinglimited thereto, the gate driver 804 a can supply another signal.

The source driver 804 b includes a shift register or the like. Thesource driver 804 b receives a signal (video signal) from which a datasignal is derived, as well as a signal for driving the shift register,through the terminal portion 807. The source driver 804 b has a functionof generating a data signal to be written to the pixel circuit 801 whichis based on the video signal. In addition, the source driver 804 b has afunction of controlling output of a data signal in response to a pulsesignal produced by input of a start pulse signal, a clock signal, or thelike. Furthermore, the source driver 804 b has a function of controllingthe potentials of wirings supplied with data signals (such wirings arehereinafter referred to as data lines DL_1 to DL_Y). Alternatively, thesource driver 804 b has a function of supplying an initializationsignal. Without being limited thereto, the source driver 804 b cansupply another signal.

The source driver 804 b includes a plurality of analog switches or thelike, for example. The source driver 804 b can output, as the datasignals, signals obtained by time-dividing the video signal bysequentially turning on the plurality of analog switches. The sourcedriver 804 b may include a shift register or the like.

A pulse signal and a data signal are input to each of the plurality ofpixel circuits 801 through one of the plurality of scan lines GLsupplied with scan signals and one of the plurality of data lines DLsupplied with data signals, respectively. Writing and holding of thedata signal to and in each of the plurality of pixel circuits 801 arecontrolled by the gate driver 804 a. For example, to the pixel circuit801 in the m-th row and the n-th column (m is a natural number of lessthan or equal to X, and n is a natural number of less than or equal toY), a pulse signal is input from the gate driver 804 a through the scanline GL_m, and a data signal is input from the source driver 804 bthrough the data line DL_n in accordance with the potential of the scanline GL_m.

The protection circuit 806 illustrated in FIG. 35A is connected to, forexample, the scan line GL between the gate driver 804 a and the pixelcircuit 801. Alternatively, the protection circuit 806 is connected tothe data line DL between the source driver 804 b and the pixel circuit801. Alternatively, the protection circuit 806 can be connected to awiring between the gate driver 804 a and the terminal portion 807.Alternatively, the protection circuit 806 can be connected to a wiringbetween the source driver 804 b and the terminal portion 807. Note thatthe terminal portion 807 means a portion having terminals for inputtingpower, control signals, and video signals to the display device fromexternal circuits.

The protection circuit 806 is a circuit that electrically connects awiring connected to the protection circuit to another wiring when apotential out of a certain range is applied to the wiring connected tothe protection circuit.

As illustrated in FIG. 35A, the protection circuits 806 are provided forthe pixel portion 802 and the driver circuit portion 804, so that theresistance of the display device to overcurrent generated byelectrostatic discharge (ESD) or the like can be improved. Note that theconfiguration of the protection circuits 806 is not limited to that, andfor example, a configuration in which the protection circuits 806 areconnected to the gate driver 804 a or a configuration in which theprotection circuits 806 are connected to the source driver 804 b may beemployed. Alternatively, the protection circuits 806 may be configuredto be connected to the terminal portion 807.

In FIG. 35A, an example in which the driver circuit portion 804 includesthe gate driver 804 a and the source driver 804 b is shown; however, thestructure is not limited thereto. For example, only the gate driver 804a may be formed and a separately prepared substrate where a sourcedriver circuit is formed (e.g., a driver circuit substrate formed with asingle crystal semiconductor film or a polycrystalline semiconductorfilm) may be mounted.

Each of the plurality of pixel circuits 801 in FIG. 35A can have astructure illustrated in FIG. 35B, for example.

The pixel circuit 801 illustrated in FIG. 35B includes transistors 852and 854, a capacitor 862, and a light-emitting element 872.

One of a source electrode and a drain electrode of the transistor 852 iselectrically connected to a wiring to which a data signal is supplied(hereinafter referred to as a data line DL_n). A gate electrode of thetransistor 852 is electrically connected to a wiring to which a gatesignal is supplied (hereinafter referred to as a scan line GL_m).

The transistor 852 has a function of controlling whether to write a datasignal by being turned on or off.

One of a pair of electrodes of the capacitor 862 is electricallyconnected to a wiring to which a potential is supplied (hereinafterreferred to as a potential supply line VL_a), and the other iselectrically connected to the other of the source electrode and thedrain electrode of the transistor 852.

The capacitor 862 functions as a storage capacitor for storing writtendata.

One of a source electrode and a drain electrode of the transistor 854 iselectrically connected to the potential supply line VL_a. Furthermore, agate electrode of the transistor 854 is electrically connected to theother of the source electrode and the drain electrode of the transistor852.

One of an anode and a cathode of the light-emitting element 872 iselectrically connected to a potential supply line VL_b, and the other iselectrically connected to the other of the source electrode and thedrain electrode of the transistor 854.

As the light-emitting element 872, any of the light-emitting elementsdescribed in Embodiment 1 can be used.

Note that a high power supply potential VDD is supplied to one of thepotential supply line VL_a and the potential supply line VL_b, and a lowpower supply potential VSS is supplied to the other.

In the display device including the pixel circuits 801 in FIG. 35B, thepixel circuits 801 are sequentially selected row by row by the gatedriver 804 a in FIG. 35A, for example, whereby the transistors 852 areturned on and a data signal is written.

When the transistors 852 are turned off, the pixel circuits 801 in whichthe data has been written are brought into a holding state. Furthermore,the amount of current flowing between the source electrode and the drainelectrode of the transistor 854 is controlled in accordance with thepotential of the written data signal. The light-emitting element 872emits light with a luminance corresponding to the amount of flowingcurrent. This operation is sequentially performed row by row; thus, animage is displayed.

Alternatively, the pixel circuit can have a function of compensatingvariation in threshold voltages or the like of a transistor. FIGS. 36Aand 36B and FIGS. 37A and 37B illustrate examples of the pixel circuit.

The pixel circuit illustrated in FIG. 36A includes six transistors(transistors 303_1 to 303_6), a capacitor 304, and a light-emittingelement 305. The pixel circuit illustrated in FIG. 36A is electricallyconnected to wirings 301_1 to 301_5 and wirings 302_1 and 302_2. Notethat as the transistors 303_1 to 303_6, for example, p-channeltransistors can be used.

The pixel circuit illustrated in FIG. 36B has a configuration in which atransistor 303_7 is added to the pixel circuit illustrated in FIG. 36A.The pixel circuit illustrated in FIG. 36B is electrically connected towirings 301_6 and 301_7. The wirings 301_5 and 301_6 may be electricallyconnected to each other. Note that as the transistor 303_7, for example,a p-channel transistor can be used.

The pixel circuit illustrated in FIG. 37A includes six transistors(transistors 308_1 to 308_6), the capacitor 304, and the light-emittingelement 305. The pixel circuit illustrated in FIG. 37A is electricallyconnected to wirings 306_1 to 306_3 and wirings 307_1 to 307_3. Thewirings 306_1 and 306_3 may be electrically connected to each other.Note that as the transistors 308_1 to 308_6, for example, p-channeltransistors can be used.

The pixel circuit illustrated in FIG. 37B includes two transistors(transistors 309_1 and 309_2), two capacitors (capacitors 304_1 and304_2), and the light-emitting element 305. The pixel circuitillustrated in FIG. 37B is electrically connected to wirings 311_1 to311_3 and wirings 312_1 and 312_2. With the configuration of the pixelcircuit illustrated in FIG. 37B, the light-emitting element 305 can bedriven by constant voltage constant current (CVCC). Note that as thetransistors 309_1 and 309_2, for example, p-channel transistors can beused.

A light-emitting element of one embodiment of the present invention canbe used for an active matrix method in which an active element isincluded in a pixel of a display device or a passive matrix method inwhich an active element is not included in a pixel of a display device.

In the active matrix method, as an active element (a non-linearelement), not only a transistor but also a variety of active elements(non-linear elements) can be used. For example, a metal insulator metal(MIM), a thin film diode (TFD), or the like can also be used. Sincethese elements can be formed with a smaller number of manufacturingsteps, manufacturing cost can be reduced or yield can be improved.Alternatively, since the size of these elements is small, the apertureratio can be improved, so that power consumption can be reduced orhigher luminance can be achieved.

As a method other than the active matrix method, the passive matrixmethod in which an active element (a non-linear element) is not used canalso be used. Since an active element (a non-linear element) is notused, the number of manufacturing steps is small, so that manufacturingcost can be reduced or yield can be improved. Alternatively, since anactive element (a non-linear element) is not used, the aperture ratiocan be improved, so that power consumption can be reduced or higherluminance can be achieved, for example.

The structure described in this embodiment can be combined with any ofthe structures described in the other embodiments and examples asappropriate.

Embodiment 4

In this embodiment, a display panel including a light-emitting device ofone embodiment of the present invention and an electronic device inwhich the display panel is provided with an input device will bedescribed with reference to FIGS. 38A and 38B, FIGS. 39A to 39C, FIGS.40A and 40B, FIGS. 41A and 41B, and FIG. 42.

<Description 1 of Touch Panel>

In this embodiment, a touch panel 2000 including a display panel and aninput device will be described as an example of an electronic device. Inaddition, an example in which a touch sensor is used as an input devicewill be described. Note that a light-emitting device of one embodimentof the present invention can be used for a pixel of the display panel.

FIGS. 38A and 38B are perspective views of the touch panel 2000. Notethat FIGS. 38A and 38B illustrate only main components of the touchpanel 2000 for simplicity.

The touch panel 2000 includes a display panel 2501 and a touch sensor2595 (see FIG. 38B). The touch panel 2000 also includes a substrate2510, a substrate 2570, and a substrate 2590. The substrate 2510, thesubstrate 2570, and the substrate 2590 each have flexibility. Note thatone or all of the substrates 2510, 2570, and 2590 may be inflexible.

The display panel 2501 includes a plurality of pixels over the substrate2510 and a plurality of wirings 2511 through which signals are suppliedto the pixels. The plurality of wirings 2511 are led to an outer portionof the substrate 2510, and parts of the plurality of wirings 2511 form aterminal 2519. The terminal 2519 is electrically connected to an FPC2509(1).

The substrate 2590 includes the touch sensor 2595 and a plurality ofwirings 2598 electrically connected to the touch sensor 2595. Theplurality of wirings 2598 are led to an outer portion of the substrate2590, and parts of the plurality of wirings 2598 form a terminal. Theterminal is electrically connected to an FPC 2509(2). Note that in FIG.38B, electrodes, wirings, and the like of the touch sensor 2595 providedon the back side of the substrate 2590 (the side facing the substrate2510) are indicated by solid lines for clarity.

As the touch sensor 2595, a capacitive touch sensor can be used.Examples of the capacitive touch sensor include a surface capacitivetouch sensor and a projected capacitive touch sensor.

Examples of the projected capacitive touch sensor are a self capacitivetouch sensor and a mutual capacitive touch sensor, which differ mainlyin the driving method. The use of a mutual capacitive type is preferablebecause multiple points can be sensed simultaneously.

Note that the touch sensor 2595 illustrated in FIG. 38B is an example ofusing a projected capacitive touch sensor.

Note that a variety of sensors that can sense proximity or touch of asensing target such as a finger can be used as the touch sensor 2595.

The projected capacitive touch sensor 2595 includes electrodes 2591 andelectrodes 2592. The electrodes 2591 are electrically connected to anyof the plurality of wirings 2598, and the electrodes 2592 areelectrically connected to any of the other wirings 2598.

The electrodes 2592 each have a shape of a plurality of quadranglesarranged in one direction with one corner of a quadrangle connected toone corner of another quadrangle as illustrated in FIGS. 38A and 38B.

The electrodes 2591 each have a quadrangular shape and are arranged in adirection intersecting with the direction in which the electrodes 2592extend.

A wiring 2594 electrically connects two electrodes 2591 between whichthe electrode 2592 is positioned. The intersecting area of the electrode2592 and the wiring 2594 is preferably as small as possible. Such astructure allows a reduction in the area of a region where theelectrodes are not provided, reducing variation in transmittance. As aresult, variation in luminance of light passing through the touch sensor2595 can be reduced.

Note that the shapes of the electrodes 2591 and the electrodes 2592 arenot limited thereto and can be any of a variety of shapes. For example,a structure may be employed in which the plurality of electrodes 2591are arranged so that gaps between the electrodes 2591 are reduced asmuch as possible, and the electrodes 2592 are spaced apart from theelectrodes 2591 with an insulating layer interposed therebetween to haveregions not overlapping with the electrodes 2591. In this case, it ispreferable to provide, between two adjacent electrodes 2592, a dummyelectrode electrically insulated from these electrodes because the areaof regions having different transmittances can be reduced.

Note that for example, a transparent conductive film including indiumoxide, tin oxide, zinc oxide, or the like (e.g., a film of ITO) can begiven as a material of conductive films used for the electrode 2591, theelectrode 2592, and the wiring 2598, i.e., wirings and electrodes in thetouch panel. Moreover, for example, a low-resistance material ispreferably used as the material of the wiring and the electrode in thetouch panel. For example, silver, copper, aluminum, a carbon nanotube,graphene, or a metal halide (such as a silver halide) may be used.Alternatively, a metal nanowire including a plurality of conductors withan extremely small width (e.g., a diameter of several nanometers) may beused. Further alternatively, a net-like metal mesh with a conductor maybe used. Examples of such materials include an Ag nanowire, a Cunanowire, an Al nanowire, an Ag mesh, a Cu mesh, and an Al mesh. Forexample, in the case of using an Ag nanowire for the wiring and theelectrode in the touch panel, a visible light transmittance of 89% ormore and a sheet resistance of 40 Ω/cm² or more and 100 Ω/cm² or lesscan be achieved. A metal nanowire, a metal mesh, a carbon nanotube,graphene, and the like, which are examples of a material that can beused for the above-described wiring and electrode in the touch panel,have a high visible light transmittance; therefore, they may be used foran electrode of a display element (e.g., a pixel electrode or a commonelectrode).

<Display Panel>

Next, the display panel 2501 is described in detail with reference toFIG. 39A. FIG. 39A is a cross-sectional view along dashed-dotted lineX1-X2 in FIG. 38B.

The display panel 2501 includes a plurality of pixels arranged in amatrix. Each of the pixels includes a display element and a pixelcircuit for driving the display element.

For the substrate 2510 and the substrate 2570, for example, a flexiblematerial with a vapor permeability lower than or equal to 10⁻⁵g/(m²·day), preferably lower than or equal to 1×10⁻⁶ g/(m²·day) can bepreferably used. Alternatively, materials whose thermal expansioncoefficients are substantially equal to each other are preferably usedfor the substrate 2510 and the substrate 2570. For example, thecoefficients of linear expansion of the materials are preferably lowerthan or equal to 1×10⁻³/K, further preferably lower than or equal to5×10⁻⁵/K and still further preferably lower than or equal to 1×10⁻⁵/K.

Note that the substrate 2510 is a stacked body including an insulatinglayer 2510 a for preventing impurity diffusion into the light-emittingelement, a flexible substrate 2510 b, and an adhesive layer 2510 c forattaching the insulating layer 2510 a and the flexible substrate 2510 bto each other. The substrate 2570 is a stacked body including aninsulating layer 2570 a for preventing impurity diffusion into thelight-emitting element, a flexible substrate 2570 b, and an adhesivelayer 2570 c for attaching the insulating layer 2570 a and the flexiblesubstrate 2570 b to each other.

For the adhesive layer 2510 c and the adhesive layer 2570 c, forexample, materials that include polyester, polyolefin, polyamide (e.g.,nylon, aramid), polyimide, polycarbonate, polyurethane, an acrylicresin, an epoxy resin, or a resin having a siloxane bond can be used.

A sealing layer 2560 is provided between the substrate 2510 and thesubstrate 2570. The sealing layer 2560 preferably has a refractive indexhigher than that of air. In the case where light is extracted to thesealing layer 2560 side as illustrated in FIG. 39A, the sealing layer2560 can also serve as an optical layer.

A sealant may be formed in the outer portion of the sealing layer 2560.With the use of the sealant, a light-emitting element 2550 can beprovided in a region surrounded by the substrate 2510, the substrate2570, the sealing layer 2560, and the sealant. Note that an inert gas(such as nitrogen or argon) may be used instead of the sealing layer2560. A drying agent may be provided in the inert gas so as to adsorbmoisture or the like. For example, an epoxy-based resin or a glass fritis preferably used as the sealant. As a material used for the sealant, amaterial which is impermeable to moisture or oxygen is preferably used.

The display panel 2501 includes a pixel 2502. The pixel 2502 includes alight-emitting module 2580.

The pixel 2502 includes the light-emitting element 2550 and a transistor2502 t that can supply electric power to the light-emitting element2550. Note that the transistor 2502 t functions as part of the pixelcircuit. The light-emitting module 2580 includes the light-emittingelement 2550 and a coloring layer 2567R.

The light-emitting element 2550 includes a lower electrode, an upperelectrode, and an EL layer between the lower electrode and the upperelectrode. As the light-emitting element 2550, any of the light-emittingelements described in Embodiments 1 to 3 can be used, for example. Notethat although only one light-emitting element 2550 is illustrated inFIG. 39A, it is possible to employ the structure with three kinds oflight-emitting elements of a first light-emitting element, a secondlight-emitting element, and a third light-emitting element as describedin Embodiment 1.

In the case where the sealing layer 2560 is provided on the lightextraction side, the sealing layer 2560 is in contact with thelight-emitting element 2550 and the coloring layer 2567R.

The coloring layer 2567R is provided to overlap with the light-emittingelement 2550. Accordingly, part of light emitted from the light-emittingelement 2550 passes through the coloring layer 2567R and is emitted tothe outside of the light-emitting module 2580 as indicated by an arrowin FIG. 39A.

The display panel 2501 includes a light-blocking layer 2567BM on thelight extraction side. The light-blocking layer 2567BM is provided so asto surround the coloring layer 2567R.

The coloring layer 2567R is a coloring layer having a function oftransmitting light in a particular wavelength range. For example, acolor filter for transmitting light in a red wavelength range, a colorfilter for transmitting light in a green wavelength range, a colorfilter for transmitting light in a blue wavelength range, a color filterfor transmitting light in a yellow wavelength range, or the like can beused. Each color filter can be formed with any of various materials by aprinting method, an inkjet method, an etching method using aphotolithography technique, or the like.

An insulating layer 2521 is provided in the display panel 2501. Theinsulating layer 2521 covers the transistor 2502 t. Note that theinsulating layer 2521 has a function of planarizing unevenness caused bythe pixel circuit. The insulating layer 2521 may have a function ofsuppressing impurity diffusion. This can prevent the reliability of thetransistor 2502 t or the like from being lowered by impurity diffusion.

The light-emitting element 2550 is formed over the insulating layer2521. A partition 2528 is provided so as to overlap with an end portionof the lower electrode of the light-emitting element 2550. Note that aspacer for controlling the distance between the substrate 2510 and thesubstrate 2570 may be formed over the partition 2528.

A scan line driver circuit 2503 g includes a transistor 2503 t and acapacitor 2503 c. Note that the driver circuit can be formed in the sameprocess and over the same substrate as those of the pixel circuits.

The wirings 2511 through which signals can be supplied are provided overthe substrate 2510. The terminal 2519 is provided over the wiring 2511.The FPC 2509(1) is electrically connected to the terminal 2519. The FPC2509(1) has a function of supplying a video signal, a clock signal, astart signal, a reset signal, or the like. Note that the FPC 2509(1) maybe provided with a printed wiring board (PWB).

In the display panel 2501, transistors with any of a variety ofstructures can be used. FIG. 39A illustrates an example of usingbottom-gate transistors; however, the present invention is not limitedto this example, and top-gate transistors may be used in the displaypanel 2501 as illustrated in FIG. 39B.

In addition, there is no particular limitation on the polarity of thetransistor 2502 t and the transistor 2503 t. For these transistors,n-channel and p-channel transistors may be used, or either n-channeltransistors or p-channel transistors may be used, for example.Furthermore, there is no particular limitation on the crystallinity of asemiconductor film used for the transistors 2502 t and 2503 t. Forexample, an amorphous semiconductor film or a crystalline semiconductorfilm may be used. Examples of semiconductor materials include Group 13semiconductors (e.g., a semiconductor including gallium), Group 14semiconductors (e.g., a semiconductor including silicon), compoundsemiconductors (including oxide semiconductors), organic semiconductors,and the like. It is preferable to use an oxide semiconductor that has anenergy gap of 2 eV or more, preferably 2.5 eV or more and furtherpreferably 3 eV or more, for one of the transistors 2502 t and 2503 t orboth, in which case the off-state current of the transistors can bereduced. Examples of the oxide semiconductors include an In—Ga oxide, anIn-M-Zn oxide (M represents Al, Ga, Y, Zr, La, Ce, Sn, or Nd), and thelike.

<Touch Sensor>

Next, the touch sensor 2595 is described in detail with reference toFIG. 39C. FIG. 39C is a cross-sectional view along dashed-dotted lineX3-X4 in FIG. 38B.

The touch sensor 2595 includes the electrodes 2591 and the electrodes2592 provided in a staggered arrangement on the substrate 2590, aninsulating layer 2593 covering the electrodes 2591 and the electrodes2592, and the wiring 2594 that electrically connects the adjacentelectrodes 2591 to each other.

The electrodes 2591 and the electrodes 2592 are formed using alight-transmitting conductive material. As a light-transmittingconductive material, a conductive oxide such as indium oxide, indium tinoxide, indium zinc oxide, zinc oxide, or zinc oxide to which gallium isadded can be used. Note that a film including graphene may be used aswell. The film including graphene can be formed, for example, byreducing a film containing graphene oxide. As a reducing method, amethod with application of heat or the like can be employed.

The electrodes 2591 and the electrodes 2592 may be formed by, forexample, depositing a light-transmitting conductive material on thesubstrate 2590 by a sputtering method and then removing an unnecessaryportion by any of various pattern forming techniques such asphotolithography.

Examples of a material for the insulating layer 2593 are a resin such asan acrylic resin or an epoxy resin, a resin having a siloxane bond, andan inorganic insulating material such as silicon oxide, siliconoxynitride, or aluminum oxide.

Openings reaching the electrodes 2591 are formed in the insulating layer2593, and the wiring 2594 electrically connects the adjacent electrodes2591. A light-transmitting conductive material can be preferably used asthe wiring 2594 because the aperture ratio of the touch panel can beincreased. Moreover, a material with higher conductivity than theconductivities of the electrodes 2591 and 2592 can be preferably usedfor the wiring 2594 because electric resistance can be reduced.

One electrode 2592 extends in one direction, and a plurality ofelectrodes 2592 are provided in the form of stripes. The wiring 2594intersects with the electrode 2592.

Adjacent electrodes 2591 are provided with one electrode 2592 providedtherebetween. The wiring 2594 electrically connects the adjacentelectrodes 2591.

Note that the plurality of electrodes 2591 are not necessarily arrangedin the direction orthogonal to one electrode 2592 and may be arranged tointersect with one electrode 2592 at an angle of more than 0 degrees andless than 90 degrees.

The wiring 2598 is electrically connected to any of the electrodes 2591and 2592. Part of the wiring 2598 functions as a terminal. For thewiring 2598, a metal material such as aluminum, gold, platinum, silver,nickel, titanium, tungsten, chromium, molybdenum, iron, cobalt, copper,or palladium or an alloy material containing any of these metalmaterials can be used.

Note that an insulating layer that covers the insulating layer 2593 andthe wiring 2594 may be provided to protect the touch sensor 2595.

A connection layer 2599 electrically connects the wiring 2598 to the FPC2509(2).

As the connection layer 2599, any of various anisotropic conductivefilms (ACF), anisotropic conductive pastes (ACP), or the like can beused.

<Description 2 of Touch Panel>

Next, the touch panel 2000 is described in detail with reference to FIG.40A. FIG. 40A is a cross-sectional view along dashed-dotted line X5-X6in FIG. 38A.

In the touch panel 2000 illustrated in FIG. 40A, the display panel 2501described with reference to FIG. 39A and the touch sensor 2595 describedwith reference to FIG. 39C are attached to each other.

The touch panel 2000 illustrated in FIG. 40A includes an adhesive layer2597 and an anti-reflective layer 2567 p in addition to the componentsdescribed with reference to FIGS. 39A and 39C.

The adhesive layer 2597 is provided in contact with the wiring 2594.Note that the adhesive layer 2597 attaches the substrate 2590 to thesubstrate 2570 so that the touch sensor 2595 overlaps with the displaypanel 2501. The adhesive layer 2597 preferably has a light-transmittingproperty. A heat curable resin or an ultraviolet curable resin can beused for the adhesive layer 2597. For example, an acrylic resin, anurethane-based resin, an epoxy-based resin, or a siloxane-based resincan be used.

The anti-reflective layer 2567 p is provided to overlap with pixels. Asthe anti-reflective layer 2567 p, a circularly polarizing plate can beused, for example.

Next, a touch panel having a structure different from that illustratedin FIG. 40A is described with reference to FIG. 40B.

FIG. 40B is a cross-sectional view of a touch panel 2001. The touchpanel 2001 illustrated in FIG. 40B differs from the touch panel 2000illustrated in FIG. 40A in the position of the touch sensor 2595relative to the display panel 2501. Different parts are described indetail below, and the above description of the touch panel 2000 isreferred to for the other similar parts.

The coloring layer 2567R is provided to overlap with the light-emittingelement 2550. The light-emitting element 2550 illustrated in FIG. 40Bemits light to the side where the transistor 2502 t is provided.Accordingly, part of light emitted from the light-emitting element 2550passes through the coloring layer 2567R and is emitted to the outside ofthe light-emitting module 2580 as indicated by an arrow in FIG. 40B.

The touch sensor 2595 is provided on the substrate 2510 side of thedisplay panel 2501.

The adhesive layer 2597 is provided between the substrate 2510 and thesubstrate 2590 and attaches the touch sensor 2595 to the display panel2501.

As illustrated in FIG. 40A or 40B, light may be emitted from thelight-emitting element to one of upper and lower sides, or both, of thesubstrate.

<Method for Driving Touch Panel>

Next, an example of a method for driving a touch panel is described withreference to FIGS. 41A and 41B.

FIG. 41A is a block diagram illustrating the structure of a mutualcapacitive touch sensor. FIG. 41A illustrates a pulse voltage outputcircuit 2601 and a current sensing circuit 2602. Note that in FIG. 41A,six wirings X1 to X6 represent the electrodes 2621 to which a pulsevoltage is applied, and six wirings Y1 to Y6 represent the electrodes2622 that detect changes in current. FIG. 41A also illustratescapacitors 2603 that are each formed in a region where the electrodes2621 and 2622 overlap with each other. Note that functional replacementbetween the electrodes 2621 and 2622 is possible.

The pulse voltage output circuit 2601 is a circuit for sequentiallyapplying a pulse voltage to the wirings X1 to X6. By application of apulse voltage to the wirings X1 to X6, an electric field is generatedbetween the electrodes 2621 and 2622 of the capacitor 2603. When theelectric field between the electrodes is shielded, for example, a changeoccurs in the capacitor 2603 (mutual capacitance). The approach orcontact of a sensing target can be sensed by utilizing this change.

The current sensing circuit 2602 is a circuit for detecting changes incurrent flowing through the wirings Y1 to Y6 that are caused by thechange in mutual capacitance in the capacitor 2603. No change in currentvalue is detected in the wirings Y1 to Y6 when there is no approach orcontact of a sensing target, whereas a decrease in current value isdetected when mutual capacitance is decreased owing to the approach orcontact of a sensing target. Note that an integrator circuit or the likeis used for detection of current values.

FIG. 41B is a timing chart showing input and output waveforms in themutual capacitive touch sensor illustrated in FIG. 41A. In FIG. 41B,sensing of a sensing target is performed in all the rows and columns inone frame period. FIG. 41B shows a period when a sensing target is notsensed (not touched) and a period when a sensing target is sensed(touched). Sensed current values of the wirings Y1 to Y6 are shown asthe waveforms of voltage values.

A pulse voltage is sequentially applied to the wirings X1 to X6, and thewaveforms of the wirings Y1 to Y6 change in accordance with the pulsevoltage. When there is no approach or contact of a sensing target, thewaveforms of the wirings Y1 to Y6 change in accordance with changes inthe voltages of the wirings X1 to X6. The current value is decreased atthe point of approach or contact of a sensing target and accordingly thewaveform of the voltage level changes.

By detecting a change in mutual capacitance in this manner, proximity orcontact of an object can be sensed.

<Sensor Circuit>

Although FIG. 41A illustrates a passive type touch sensor in which onlythe capacitor 2603 is provided at the intersection of wirings as a touchsensor, an active type touch sensor including a transistor and acapacitor may be used. FIG. 42 illustrates an example of a sensorcircuit included in an active type touch sensor.

The sensor circuit in FIG. 42 includes the capacitor 2603 andtransistors 2611, 2612, and 2613.

A signal G2 is input to a gate of the transistor 2613. A voltage VRES isapplied to one of a source and a drain of the transistor 2613, and oneelectrode of the capacitor 2603 and a gate of the transistor 2611 areelectrically connected to the other of the source and the drain of thetransistor 2613. One of a source and a drain of the transistor 2611 iselectrically connected to one of a source and a drain of the transistor2612, and a voltage VSS is applied to the other of the source and thedrain of the transistor 2611. A signal G1 is input to a gate of thetransistor 2612, and a wiring ML is electrically connected to the otherof the source and the drain of the transistor 2612. The voltage VSS isapplied to the other electrode of the capacitor 2603.

Next, the operation of the sensor circuit in FIG. 42 will be described.First, a potential for turning on the transistor 2613 is supplied as thesignal G2, and a potential with respect to the voltage VRES is thusapplied to the node n connected to the gate of the transistor 2611.Then, a potential for turning off the transistor 2613 is applied as thesignal G2, whereby the potential of the node n is maintained.

Then, mutual capacitance of the capacitor 2603 changes owing to theapproach or contact of a sensing target such as a finger, andaccordingly the potential of the node n is changed from VRES.

In reading operation, a potential for turning on the transistor 2612 issupplied as the signal G1. A current flowing through the transistor2611, that is, a current flowing through the wiring ML is changed inaccordance with the potential of the node n. By sensing this current,the approach or contact of a sensing target can be sensed.

In each of the transistors 2611, 2612, and 2613, an oxide semiconductorlayer is preferably used as a semiconductor layer in which a channelregion is formed. In particular, such a transistor is preferably used asthe transistor 2613 so that the potential of the node n can be held fora long time and the frequency of operation of resupplying VRES to thenode n (refresh operation) can be reduced.

The structure described in this embodiment can be combined with any ofthe structures described in the other embodiments and examples asappropriate.

Embodiment 5

In this embodiment, a display module and electronic devices including alight-emitting element of one embodiment of the present invention willbe described with reference to FIG. 43 and FIGS. 44A to 44G.

In a display module 8000 illustrated in FIG. 43, a touch sensor 8004connected to an FPC 8003, a display panel 8006 connected to an FPC 8005,a frame 8009, a printed board 8010, and a battery 8011 are providedbetween an upper cover 8001 and a lower cover 8002.

The light-emitting device of one embodiment of the present invention canbe used for the display panel 8006, for example.

The shapes and sizes of the upper cover 8001 and the lower cover 8002can be changed as appropriate in accordance with the sizes of the touchsensor 8004 and the display panel 8006.

The touch sensor 8004 can be a resistive touch sensor or a capacitivetouch sensor and may be formed to overlap with the display panel 8006. Acounter substrate (sealing substrate) of the display panel 8006 can havea touch sensor function. A photosensor may be provided in each pixel ofthe display panel 8006 so that an optical touch sensor is obtained.

The frame 8009 protects the display panel 8006 and also serves as anelectromagnetic shield for blocking electromagnetic waves generated bythe operation of the printed board 8010. The frame 8009 may serve as aradiator plate.

The printed board 8010 has a power supply circuit and a signalprocessing circuit for outputting a video signal and a clock signal. Asa power source for supplying power to the power supply circuit, anexternal commercial power source or the battery 8011 provided separatelymay be used. The battery 8011 can be omitted in the case of using acommercial power source.

The display module 8000 can be additionally provided with a member suchas a polarizing plate, a retardation plate, or a prism sheet.

FIGS. 44A to 44G illustrate electronic devices. These electronic devicescan include a housing 9000, a display portion 9001, a speaker 9003,operation keys 9005, a connection terminal 9006, a sensor 9007, amicrophone 9008, and the like.

The electronic devices illustrated in FIGS. 44A to 44G can have avariety of functions, for example, a function of displaying a variety ofdata (a still image, a moving image, a text image, and the like) on thedisplay portion, a touch sensor function, a function of displaying acalendar, date, time, and the like, a function of controlling a processwith a variety of software (programs), a wireless communicationfunction, a function of being connected to a variety of computernetworks with a wireless communication function, a function oftransmitting and receiving a variety of data with a wirelesscommunication function, a function of reading a program or data storedin a memory medium and displaying the program or data on the displayportion, and the like. Note that functions that can be provided for theelectronic devices illustrated in FIGS. 44A to 44G are not limited tothose described above, and the electronic devices can have a variety offunctions. Although not illustrated in FIGS. 44A to 44G, the electronicdevices may include a plurality of display portions. The electronicdevices may have a camera or the like and a function of taking a stillimage, a function of taking a moving image, a function of storing thetaken image in a memory medium (an external memory medium or a memorymedium incorporated in the camera), a function of displaying the takenimage on the display portion, or the like.

The electronic devices illustrated in FIGS. 44A to 44G are described indetail below.

FIG. 44A is a perspective view of a portable information terminal 9100.The display portion 9001 of the portable information terminal 9100 isflexible. Therefore, the display portion 9001 can be incorporated alonga bent surface of a bent housing 9000. In addition, the display portion9001 includes a touch sensor, and operation can be performed by touchingthe screen with a finger, a stylus, or the like. For example, when anicon displayed on the display portion 9001 is touched, an applicationcan be started.

FIG. 44B is a perspective view of a portable information terminal 9101.The portable information terminal 9101 functions as, for example, one ormore of a telephone set, a notebook, and an information browsing system.Specifically, the portable information terminal can be used as asmartphone. Note that the speaker 9003, the connection terminal 9006,the sensor 9007, and the like, which are not shown in FIG. 44B, can bepositioned in the portable information terminal 9101 as in the portableinformation terminal 9100 shown in FIG. 44A. The portable informationterminal 9101 can display characters and image information on itsplurality of surfaces. For example, three operation buttons 9050 (alsoreferred to as operation icons, or simply, icons) can be displayed onone surface of the display portion 9001. Furthermore, information 9051indicated by dashed rectangles can be displayed on another surface ofthe display portion 9001. Examples of the information 9051 includedisplay indicating reception of an incoming email, social networkingservice (SNS) message, call, and the like; the title and sender of anemail and SNS message; the date; the time; remaining battery; and thereception strength of an antenna. Instead of the information 9051, theoperation buttons 9050 or the like may be displayed on the positionwhere the information 9051 is displayed.

FIG. 44C is a perspective view of a portable information terminal 9102.The portable information terminal 9102 has a function of displayinginformation on three or more surfaces of the display portion 9001. Here,information 9052, information 9053, and information 9054 are displayedon different surfaces. For example, a user of the portable informationterminal 9102 can see the display (here, the information 9053) with theportable information terminal 9102 put in a breast pocket of his/herclothes. Specifically, a caller's phone number, name, or the like of anincoming call is displayed in a position that can be seen from above theportable information terminal 9102. Thus, the user can see the displaywithout taking out the portable information terminal 9102 from thepocket and decide whether to answer the call.

FIG. 44D is a perspective view of a watch-type portable informationterminal 9200. The portable information terminal 9200 is capable ofexecuting a variety of applications such as mobile phone calls,e-mailing, viewing and editing texts, music reproduction, Internetcommunication, and computer games. The display surface of the displayportion 9001 is bent, and images can be displayed on the bent displaysurface. The portable information terminal. 9200 can employ near fieldcommunication that is a communication method based on an existingcommunication standard. In that case, for example, mutual communicationbetween the portable information terminal 9200 and a headset capable ofwireless communication can be performed, and thus hands-free calling ispossible. The portable information terminal 9200 includes the connectionterminal 9006, and data can be directly transmitted to and received fromanother information terminal via a connector. Power charging through theconnection terminal 9006 is possible. Note that the charging operationmay be performed by wireless power feeding without using the connectionterminal 9006.

FIGS. 44E, 44F, and 44G are perspective views of a foldable portableinformation terminal 9201. FIG. 44E is a perspective view illustratingthe portable information terminal 9201 that is opened. FIG. 44F is aperspective view illustrating the portable information terminal 9201that is being opened or being folded. FIG. 44G is a perspective viewillustrating the portable information terminal 9201 that is folded. Theportable information terminal 9201 is highly portable when folded. Whenthe portable information terminal 9201 is opened, a seamless largedisplay region is highly browsable. The display portion 9001 of theportable information terminal 9201 is supported by three housings 9000joined together by hinges 9055. By folding the portable informationterminal 9201 at a connection portion between two housings 9000 with thehinges 9055, the portable information terminal 9201 can be reversiblychanged in shape from an opened state to a folded state. For example,the portable information terminal 9201 can be bent with a radius ofcurvature of greater than or equal to 1 mm and less than or equal to 150mm.

The electronic devices described in this embodiment each include thedisplay portion for displaying some sort of data. Note that thelight-emitting device of one embodiment of the present invention canalso be used for an electronic device which does not have a displayportion. The structure in which the display portion of the electronicdevice described in this embodiment is flexible and display can beperformed on the bent display surface or the structure in which thedisplay portion of the electronic device is foldable is described as anexample; however, the structure is not limited thereto and a structurein which the display portion of the electronic device is not flexibleand display is performed on a plane portion may be employed.

The structure described in this embodiment can be combined with any ofthe structures described in the other embodiments and examples asappropriate.

Embodiment 6

In this embodiment, the light-emitting device of one embodiment of thepresent invention will be described with reference to FIGS. 45A to 45C.

FIG. 45A is a perspective view of a light-emitting device 3000 shown inthis embodiment, and FIG. 45B is a cross-sectional view alongdashed-dotted line E-F in FIG. 45A. Note that in FIG. 45A, somecomponents are illustrated by broken lines in order to avoid complexityof the drawing.

The light-emitting device 3000 illustrated in FIGS. 45A and 45B includesa substrate 3001, a light-emitting element 3005 over the substrate 3001,a first sealing region 3007 provided around the light-emitting element3005, and a second sealing region 3009 provided around the first sealingregion 3007.

Light is emitted from the light-emitting element 3005 through one orboth of the substrate 3001 and a substrate 3003. In FIGS. 45A and 45B, astructure in which light is emitted from the light-emitting element 3005to the lower side (the substrate 3001 side) is illustrated.

As illustrated in FIGS. 45A and 45B, the light-emitting device 3000 hasa double sealing structure in which the light-emitting element 3005 issurrounded by the first sealing region 3007 and the second sealingregion 3007. With the double sealing structure, entry of impurities(e.g., water, oxygen, and the like) from the outside into thelight-emitting element 3005 can be preferably suppressed. Note that itis not necessary to provide both the first sealing region 3007 and thesecond sealing region 3009. For example, only the first sealing region3007 may be provided.

Note that in FIG. 45B, the first sealing region 3007 and the secondsealing region 3009 are each provided in contact with the substrate 3001and the substrate 3003. However, without limitation to such a structure,for example, one or both of the first sealing region 3007 and the secondsealing region 3009 may be provided in contact with an insulating filmor a conductive film provided on the substrate 3001. Alternatively, oneor both of the first sealing region 3007 and the second sealing region3009 may be provided in contact with an insulating film or a conductivefilm provided on the substrate 3003.

The substrate 3001 and the substrate 3003 can have structures similar tothose of the substrate 102 and the substrate 152 described in Embodiment1, respectively. The light-emitting element 3005 can have a structuresimilar to that of any of the first to third light-emitting elementsdescribed in Embodiment 1.

For the first sealing region 3007, a material containing glass (e.g., aglass frit, a glass ribbon, and the like) can be used. For the secondsealing region 3009, a material containing a resin can be used. With theuse of the material containing glass for the first sealing region 3007,productivity and a sealing property can be improved. Moreover, with theuse of the material containing a resin for the second sealing region3009, impact resistance and heat resistance can be improved. However,the materials used for the first sealing region 3007 and the secondsealing region 3009 are not limited to such, and the first sealingregion 3007 may be formed using the material containing a resin and thesecond sealing region 3009 may be formed using the material containingglass.

The glass frit may contain, for example, magnesium oxide, calcium oxide,strontium oxide, barium oxide, cesium oxide, sodium oxide, potassiumoxide, boron oxide, vanadium oxide, zinc oxide, tellurium oxide,aluminum oxide, silicon dioxide, lead oxide, tin oxide, phosphorusoxide, ruthenium oxide, rhodium oxide, iron oxide, copper oxide,manganese dioxide, molybdenum oxide, niobium oxide, titanium oxide,tungsten oxide, bismuth oxide, zirconium oxide, lithium oxide, antimonyoxide, lead borate glass, tin phosphate glass, vanadate glass, orborosilicate glass. The glass fit preferably contains at least one kindof transition metal to absorb infrared light.

As the above glass frits, for example, a frit paste is applied to asubstrate and is subjected to heat treatment, laser light irradiation,or the like. The frit paste contains the glass frit and a resin (alsoreferred to as a binder) diluted by an organic solvent. Note that anabsorber which absorbs light having the wavelength of laser light may beadded to the glass frit. For example, an Nd:YAG laser or a semiconductorlaser is preferably used as the laser. The shape of laser light may becircular or quadrangular.

As the above material containing a resin, for example, materials thatinclude polyester, polyolefin, polyamide (e.g., nylon, aramid),polyimide, polycarbonate, polyurethane, an acrylic resin, an epoxyresin, or a resin having a siloxane bond can be used.

Note that in the case where the material containing glass is used forone or both of the first sealing region 3007 and the second sealingregion 3009, the material containing glass preferably has a thermalexpansion coefficient close to that of the substrate 3001. With theabove structure, generation of a crack in the material containing glassor the substrate 3001 due to thermal stress can be suppressed.

For example, the following advantageous effect can be obtained in thecase where the material containing glass is used for the first sealingregion 3007 and the material containing a resin is used for the secondsealing region 3009.

The second sealing region 3009 is provided closer to an outer portion ofthe light-emitting device 3000 than the first sealing region 3007 is. Inthe light-emitting device 3000, distortion due to external force or thelike increases toward the outer portion. Thus, the outer portion of thelight-emitting device 3000 where a larger amount of distortion isgenerated, that is, the second sealing region 3009 is sealed using thematerial containing a resin and the first sealing region 3007 providedon an inner side of the second region 3009 is sealed using the materialcontaining glass, whereby the light-emitting device 3000 is less likelyto be damaged even when distortion due to external force or the like isgenerated.

Furthermore, as illustrated in FIG. 45B, a first region 3011 correspondsto the region surrounded by the substrate 3001, the substrate 3003, thefirst sealing region 3007, and the second sealing region 3009. A secondregion 3013 corresponds to the region surrounded by the substrate 3001,the substrate 3003, the light-emitting element 3005, and the firstsealing region 3007.

The first region 3011 and the second region 3013 are preferably filledwith, for example, an inert gas such as a rare gas or a nitrogen gas.Note that for the first region 3011 and the second region 3013, areduced pressure state is preferred to an atmospheric pressure state.

FIG. 45C illustrates a modification example of the structure in FIG.45B. FIG. 45C is a cross-sectional view illustrating the modificationexample of the light-emitting device 3000.

FIG. 45C illustrates a structure in which a desiccant 3018 is providedin a recessed portion provided in part of the substrate 3003. The othercomponents are the same as those of the structure illustrated in FIG.45B.

As the desiccant 3018, a substance which adsorbs moisture and the likeby chemical adsorption or a substance which adsorbs moisture and thelike by physical adsorption can be used. Examples of the substance thatcan be used as the desiccant 3018 include alkali metal oxides, alkalineearth metal oxide (e.g., calcium oxide, barium oxide, and the like),sulfate, metal halides, perchlorate, zeolite, silica gel, and the like.

Next, modification examples of the light-emitting device 3000 which isillustrated in FIG. 45B are described with reference to FIGS. 46A to46D. Note that FIGS. 46A to 46D are cross-sectional views illustratingthe modification examples of the light-emitting device 3000 illustratedin FIG. 45B.

In the light-emitting device illustrated in FIG. 46A, the second sealingregion 3009 is not provided but only the first sealing region 3007 isprovided. Moreover, in the light-emitting device illustrated in FIG.46A, a region 3014 is provided instead of the second region 3013illustrated in FIG. 45B.

For the region 3014, for example, materials that include polyester,polyolefin, polyamide (e.g., nylon, aramid), polyimide, polycarbonate,polyurethane, an acrylic resin, an epoxy resin, or a resin having asiloxane bond can be used.

When the above-described material is used for the region 3014, what iscalled a solid-sealing light-emitting device can be obtained.

In the light-emitting device illustrated in FIG. 46B, a substrate 3015is provided on the substrate 3001 side of the light-emitting deviceillustrated in FIG. 46A.

The substrate 3015 has unevenness as illustrated in FIG. 46B. With astructure in which the substrate 3015 having unevenness is provided onthe side through which light emitted from the light-emitting element3005 is extracted, the efficiency of extraction of light from thelight-emitting element 3005 can be improved. Note that instead of thestructure having unevenness and illustrated in FIG. 46B, a substratehaving a function as a diffusion plate may be provided.

In the light-emitting device illustrated in FIG. 46C, light is extractedthrough the substrate 3003 side, unlike in the light-emitting deviceillustrated in FIG. 46A, in which light is extracted through thesubstrate 3001 side.

The light-emitting device illustrated in FIG. 46C includes the substrate3015 on the substrate 3003 side. The other components are the same asthose of the light-emitting device illustrated in FIG. 46B.

In the light-emitting device illustrated in FIG. 46D, the substrate 3003and the substrate 3015 included in the light-emitting device illustratedin FIG. 46C are not provided but a substrate 3016 is provided.

The substrate 3016 includes first unevenness positioned closer to thelight-emitting element 3005 and second unevenness positioned fartherfrom the light-emitting element 3005. With the structure illustrated inFIG. 46D, the efficiency of extraction of light from the light-emittingelement 3005 can be further improved.

Thus, the use of the structure described in this embodiment can obtain alight-emitting device in which deterioration of a light-emitting elementdue to impurities such as moisture and oxygen is suppressed.Alternatively, with the structure described in this embodiment, alight-emitting device having high light extraction efficiency can beobtained.

The structure described in this embodiment can be combined with any ofthe structures described in the other embodiments and examples asappropriate.

Embodiment 7

In this embodiment, examples in which the light-emitting device of oneembodiment of the present invention is applied to various lightingdevices and electronic devices will be described with reference to FIGS.47A to 47C.

An electronic device or a lighting device that has a light-emittingregion with a curved surface can be obtained with the use of thelight-emitting device of one embodiment of the present invention whichis manufactured over a substrate having flexibility.

Furthermore, a light-emitting device to which one embodiment of thepresent invention is applied can also be applied to lighting for motorvehicles, examples of which are lighting for a dashboard, a windshield,a ceiling, and the like.

FIG. 47A is a perspective view illustrating one surface of amultifunction terminal 3500, and FIG. 47B is a perspective viewillustrating the other surface of the multifunction terminal 3500. In ahousing 3502 of the multifunction terminal 3500, a display portion 3504,a camera 3506, lighting 3508, and the like are incorporated. Thelight-emitting device of one embodiment of the present invention can beused for the lighting 3508.

The lighting 3508 that includes the light-emitting device of oneembodiment of the present invention functions as a planar light source.Thus, unlike a point light source typified by an LED, the lighting 3508can provide light emission with low directivity. When the lighting 3508and the camera 3506 are used in combination, for example, imaging can beperformed by the camera 3506 with the lighting 3508 lighting orflashing. Because the lighting 3508 functions as a planar light source,a photograph as if taken under natural light can be taken.

Note that the multifunction terminal 3500 illustrated in FIGS. 47A and47B can have a variety of functions as in the electronic devicesillustrated in FIGS. 44A to 44G.

The housing 3502 can include a speaker, a sensor (a sensor having afunction of measuring force, displacement, position, speed,acceleration, angular velocity, rotational frequency, distance, light,liquid, magnetism, temperature, chemical substance, sound, time,hardness, electric field, current, voltage, electric power, radiation,flow rate, humidity, gradient, oscillation, odor, or infrared rays), amicrophone, and the like. When a detection device including a sensor fordetecting inclination, such as a gyroscope or an acceleration sensor, isprovided inside the multifunction terminal 3500, display on the screenof the display portion 3504 can be automatically switched by determiningthe orientation of the multifunction terminal 3500 (whether themultifunction terminal is placed horizontally or vertically for alandscape mode or a portrait mode).

The display portion 3504 may function as an image sensor. For example,an image of a palm print, a fingerprint, or the like is taken when thedisplay portion 3504 is touched with the palm or the finger, wherebypersonal authentication can be performed. Furthermore, by providing abacklight or a sensing light source which emits near-infrared light inthe display portion 3504, an image of a finger vein, a palm vein, or thelike can be taken. Note that the light-emitting device of one embodimentof the present invention may be used for the display portion 3504.

FIG. 47C is a perspective view of a security light 3600. The securitylight 3600 includes lighting 3608 on the outside of the housing 3602,and a speaker 3610 and the like are incorporated in the housing 3602.The light-emitting device of one embodiment of the present invention canbe used for the lighting 3608.

The security light 3600 emits light when the lighting 3608 is gripped orheld, for example. An electronic circuit that can control the manner oflight emission from the security light 3600 may be provided in thehousing 3602. The electronic circuit may be a circuit that enables lightemission once or intermittently plural times or may be a circuit thatcan adjust the amount of emitted light by controlling the current valuefor light emission. A circuit with which a loud audible alarm is outputfrom the speaker 3610 at the same time as light emission from thelighting 3608 may be incorporated.

The security light 3600 can emit light in various directions; therefore,it is possible to intimidate a thug or the like with light, or light andsound. Moreover, the security light 3600 may include a camera such as adigital still camera to have a photography function.

As described above, lighting devices and electronic devices can beobtained by application of the light-emitting device of one embodimentof the present invention. Note that the light-emitting device can beused for lighting devices and electronic devices in a variety of fieldswithout being limited to the lighting devices and the electronic devicesdescribed in this embodiment.

The structure described in this embodiment can be combined with any ofthe structures described in the other embodiments and examples asappropriate.

Example 1

In Example 1, an example of fabricating a light-emitting element of oneembodiment of the present invention will be described. Note that inExample 1, a light-emitting element 1, a light-emitting element 2, and alight-emitting element 3 were fabricated.

A schematic cross-sectional view of the light-emitting element 1 is inFIG. 48C, a schematic cross-sectional view of the light-emitting element2 is in FIG. 48A, a schematic cross-sectional view of the light-emittingelement 3 is in FIG. 48B, the detailed structures of the light-emittingelements 1 to 3 are shown in Table 1, and structures and abbreviationsof the compounds used here are given below.

TABLE 1 Layer Reference numeral Thickness (nm) Material Weight ratioLight- Coloring layer 556 — Red*¹⁾ — emitting Upper electrode 514(2) 70ITO — element 1 514(1) 15 Ag:Mg 1:0.1*²⁾ Electron-injection 534 1 LiF —layer Electron- 533(2) 15 NBphen — transport layer 533(1) 5 cgDBCzPA —Second light- 512 25 cgDBCzPA:1,6BnfAPrn-03 1:0.05 emitting layer Firstlight-emitting 510(2) 10 2mDBTBPDBq-II:Ir(tBuppm)₂(acac) 1:0.06 layer510(1) 20 2mDBTBPDBq-II:PCBBiF:Ir(tBuppm)₂(acac) 0.8:0.2:0.06 Optical508 22.5 PCPPn — adjustment layer Hole-transport 532 22.5 PCPPn — layerHole-injection 531 35 PCPPn:MoO_(x) 2:1 layer Transparent 506 110 ITSO —conductive layer Lower electrode 504 100 APC — Light- Upper electrode514(2) 70 ITO — emitting 514(1) 15 Ag:Mg 1:0.1*²⁾ element 2Electron-injection 534 1 LiF — layer Electron- 533(2) 15 NBphen —transport layer 533(1) 5 cgDBCzPA — Second light- 512 25cgDBCzPA:1,6BnfAPrn-03 1:0.05 emitting layer First light-emitting 510(2)10 2mDBTBPDBq-II:Ir(tBuppm)₂(acac) 1:0.06 layer 510(1) 202mDBTBPDBq-II:PCBBiF:Ir(tBuppm)₂(acac) 0.8:0.2:0.06 Optical 508 22.5PCPPn — adjustment layer Hole-transport 532 22.5 PCPPn — layerHole-injection 531 25 PCPPn:MoO_(x) 2:1 layer Transparent 506 85 ITSO —conductive layer Lower electrode 504 100 APC — Light- Upper electrode514(2) 70 ITO — emitting 514(1) 15 Ag:Mg 1:0.1*²⁾ element 3Electron-injection 534 1 LiF — layer Electron- 533(2) 15 NBphen —transport layer 533(1) 5 cgDBCzPA — Second light- 512 25cgDBCzPA:1,6BnfAPrn-03 1:0.05 emitting layer First light-emitting — — —— layer — — — — Optical — — — — adjustment layer Hole-transport 532 22.5PCPPn — layer Hole-injection 531 25 PCPPn:MoO_(x) 2:1 layer Transparent506 85 ITSO — conductive layer Lower electrode 504 100 APC — *¹⁾color*²⁾volume ratio<1-1. Fabrication of Light-Emitting Elements 1 and 2>

First, over a substrate 502, an alloy film of silver (Ag), palladium(Pd), and copper (Cu) (the alloy film is hereinafter referred to as APC)was formed as a lower electrode 504 by a sputtering method. Note thatthe thickness of the lower electrode 504 was 100 nm and the area of thelower electrode 504 was 4 mm² (2 mm×2 mm).

Then, over the lower electrode 504, indium tin oxide containing siliconoxide (the film is hereinafter referred to as ITSO) was deposited as atransparent conductive layer 506 by a sputtering method. Note that thethickness of the transparent conductive layer 506 was 110 nm in thelight-emitting element 1, and the thickness of the transparentconductive layer 506 was 85 nm in the light-emitting element 2.

Then, as pretreatment of evaporation of an organic compound layer, thetransparent conductive layer 506 side of the substrate 502 provided withthe lower electrode 504 and the transparent conductive layer 506 waswashed with water, baking was performed at 200° C. for one hour, andthen UV ozone treatment was performed on a surface of the transparentconductive layer 506 for 370 seconds.

After that, the substrate 502 was transferred into a vacuum evaporationapparatus where the pressure had been reduced to approximately 10⁻⁴ Pa,and was subjected to vacuum baking at 170° C. for 60 minutes in aheating chamber of the vacuum evaporation apparatus, and then thesubstrate 502 was cooled down for about 30 minutes.

Then, the substrate 502 was fixed to a holder provided in the vacuumevaporation apparatus so that a surface of the substrate 502 over whichthe transparent conductive layer 506 was formed faced downward. InExample 1, by a vacuum evaporation method, a hole-injection layer 531, ahole-transport layer 532, an optical adjustment layer 508, a firstlight-emitting layer 510(1), a first light-emitting layer 510(2), asecond light-emitting layer 512, an electron-transport layer 533(1), anelectron-transport layer 533(2), an electron-injection layer 534, anupper electrode 514(1), and an upper electrode 514(2) were sequentiallyformed. The fabrication method is described in detail below.

First, the pressure in the vacuum evaporation apparatus was reduced to10⁻⁴ Pa. Then, on the transparent conductive layer 506, thehole-injection layer 531 was formed by co-evaporation of3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn)and molybdenum oxide at a weight ratio of 2:1 (PcPPn:molybdenum oxide).Note that the thickness of the hole-injection layer 531 was 35 nm in thelight-emitting element 1, and the thickness of the hole-injection layer531 was 25 nm in the light-emitting element 2.

Then, the hole-transport layer 532 was formed on the hole-injectionlayer 531. As the hole-transport layer 532, PCPPn was evaporated. Notethat the thickness of the hole-transport layer 532 was 22.5 nm.

Then, the optical adjustment layer 508 was formed on the hole-transportlayer 532. As the optical adjustment layer 508, PCPPn was evaporated.Note that the thickness of the optical adjustment layer 508 was 22.5 nm.

Then, the first light-emitting layer 510(1) was formed on the opticaladjustment layer 508. The first light-emitting layer 510(1) was formedby co-evaporation of2-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline(abbreviation: 2mDBTBPDBq-II),N-(1,1′-biphenyl-4-yl)-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9H-fluoren-2-amine (abbreviation: PCBBiF), and(acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III)(abbreviation: Ir(tBuppm)₂(acac)) at a weight ratio of 0.8:0.2:0.06(2mDBTBPDBq-II:PCBBiF: Ir(tBuppm)₂(acac)). Note that the thickness ofthe first light-emitting layer 510(1) was 20 nm Note that 2mDBTBPDBq-IIwas the host material, PCBBiF was the assist material, andIr(tBuppm)₂(acac) was the phosphorescent material (the guest material)in the first light-emitting layer 510(1).

Then, the first light-emitting layer 510(2) was formed on the firstlight-emitting layer 510(1). Then, the first light-emitting layer 510(2)was formed by co-evaporation of 2mDBTBPDBq-II and Ir(tBuppm)₂(acac) at aweight ratio of 1:0.06 (2mDBTBPDBq-II: Ir(tBuppm)₂(acac)). Note that thethickness of the first light-emitting layer 510(2) was 10 nm. Note that2mDBTBPDBq-II was the host material and Ir(tBuppm)₂(acac) was thephosphorescent material (the guest material) in the first light-emittinglayer 510(2).

Then, the second light-emitting layer 512 was formed on the firstlight-emitting layer 510(2). The second light-emitting layer 512 wasformed by co-evaporation of7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole(abbreviation: cgDBCzPA) andN,N′-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine](abbreviation:1,6BnfAPm-03) at a weight ratio of 1:0.05 (cgDBCzPA: 1,6BnfAPrn-03).Note that the thickness of the second light-emitting layer 512 was 25nm. Note that cgDBCzPA was the host material and 1,6BnfAPrn-03 was thefluorescent material (the guest material) in the second light-emittinglayer 512.

Then, on the second light-emitting layer 512, the electron-transportlayer 533(1) was formed by evaporation of cgDBCzPA to a thickness of 5nm. Then, on the electron-transport layer 533(1), the electron-transportlayer 533(2) was formed by evaporation of2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation:NBphen) to a thickness of 15 nm. Then, on the electron-transport layer533(2), the electron-injection layer 534 was formed by evaporation oflithium fluoride (LiF) to a thickness of 1 nm.

Then, on the electron-injection layer 534, the upper electrode 514(1)was formed by co-evaporation of silver (Ag) and magnesium (Mg) at avolume ratio of 1:0.1. Note that the thickness of the upper electrode514(1) was 15 nm. Then, on the upper electrode 514(1), indium tin oxide(ITO) was deposited as the upper electrode 514(2) by a sputtering methodto a thickness of 70 nm.

Next, a sealing substrate 550 was prepared. Note that as illustrated inFIG. 48C and shown in Table 1, the sealing substrate 550 of thelight-emitting element 1 is provided with a coloring layer 556. InExample 1, a red (R) color filter was formed as the coloring layer 556of the light-emitting element 1. Note that the sealing substrate 550 ofthe light-emitting element 2 is not provided with the coloring layer556.

Each of the light-emitting elements over the substrate 502 fabricated asdescribed above was sealed by being bonded to the sealing substrate 550in a glove box in a nitrogen atmosphere so as not to be exposed to theair (specifically, a sealant was applied to surround the element, andirradiation with ultraviolet light having a wavelength of 365 nm at 6J/cm² and heat treatment at 80° C. for one hour were performed forsealing).

Through the above process, the light-emitting elements 1 and 2 werefabricated.

<1-2. Fabrication of Light-Emitting Element 3>

First, over the substrate 502, APC was formed as the lower electrode 504by a sputtering method. Note that the thickness of the lower electrode504 was 100 nm and the area of the lower electrode 504 was 4 mm².

Then, over the lower electrode 504, ITSO was deposited as thetransparent conductive layer 506 by a sputtering method. Note that thethickness of the transparent conductive layer 506 was 85 nm.

Then, as pretreatment of evaporation of an organic compound layer, thetransparent conductive layer 506 side of the substrate 502 provided withthe lower electrode 504 and the transparent conductive layer 506 waswashed with water, baking was performed at 200° C. for one hour, andthen UV ozone treatment was performed on a surface of the transparentconductive layer 506 for 370 seconds.

After that, the substrate 502 was transferred into a vacuum evaporationapparatus where the pressure had been reduced to approximately 10⁻⁴ Pa,and was subjected to vacuum baking at 170° C. for 60 minutes in aheating chamber of the vacuum evaporation apparatus, and then thesubstrate 502 was cooled down for about 30 minutes.

Then, the substrate 502 was fixed to a holder provided in the vacuumevaporation apparatus so that a surface of the substrate 502 over whichthe transparent conductive layer 506 was formed faced downward. InExample 1, by a vacuum evaporation method, the hole-injection layer 531,the hole-transport layer 532, the second light-emitting layer 512, theelectron-transport layer 533(1), the electron-transport layer 533(2),the electron-injection layer 534, the upper electrode 514(1), and theupper electrode 514(2) were sequentially formed. That is, the opticaladjustment layer 508, the first light-emitting layer 510(1), and thefirst light-emitting layer 510(2) are not formed in the light-emittingelement 3, unlike in the light-emitting elements 1 and 2. Thefabrication method is described in detail below.

First, the pressure in the vacuum evaporation apparatus was reduced to10⁻⁴ Pa. Then, on the transparent conductive layer 506, thehole-injection layer 531 was formed by co-evaporation of PCPPn andmolybdenum oxide at a weight ratio of 2:1 (PcPPn:molybdenum oxide). Notethat the thickness of the hole-injection layer 531 was 25 nm.

Then, the hole-transport layer 532 was formed on the hole-injectionlayer 531. As the hole-transport layer 532, PCPPn was evaporated. Notethat the thickness of the hole-transport layer 532 was 22.5 nm.

Then, the second light-emitting layer 512 was formed on thehole-transport layer 532. The second light-emitting layer 512 was formedby co-evaporation of cgDBCzPA and 1,6BnfAPrn-03 at a weight ratio of1:0.05 (cgDBCzPA: 1,6BnfAPrn-03). Note that the thickness of the secondlight-emitting layer 512 was 25 nm.

Then, on the second light-emitting layer 512, the electron-transportlayer 533(1) was formed by evaporation of cgDBCzPA to a thickness of 5nm. Then, on the electron-transport layer 533(1), the electron-transportlayer 533(2) was formed by evaporation of NBphen to a thickness of 15nm. Then, on the electron-transport layer 533(2), the electron-injectionlayer 534 was formed by evaporation of LiF to a thickness of 1 nm.

Then, on the electron-injection layer 534, the upper electrode 514(1)was formed by co-evaporation of Ag and Mg at a volume ratio of 1:0.1.Note that the thickness of the upper electrode 514(1) was 15 nm. Then,on the upper electrode 514(1), ITO was deposited as the upper electrode514(2) by a sputtering method to a thickness of 70 nm.

Next, the sealing substrate 550 was prepared.

The light-emitting element over the substrate 502 fabricated asdescribed above was sealed by being bonded to the sealing substrate 550in a glove box in a nitrogen atmosphere so as not to be exposed to theair. Note that the sealing method was the same as those of thelight-emitting elements 1 and 2.

Through the above process, the light-emitting element 3 was fabricated.

Note that in all the above evaporation steps for the light-emittingelements 1 to 3, a resistive heating method was used as an evaporationmethod.

<1-3. Characteristics of Light-Emitting Elements 1 to 3>

FIGS. 49A, 49B, and 50A show luminance-current density characteristics,luminance-voltage characteristics, and current efficiency-luminancecharacteristics, respectively, of the light-emitting elements 1 to 3.Note that the measurements of the light-emitting elements were carriedout at room temperature (in an atmosphere kept at 25° C.).

Table 2 shows element characteristics of the light-emitting elements 1to 3 at around 1000 cd/m².

TABLE 2 Voltage Current Current density Chromaticity Luminance Currentefficiency (V) (mA) (mA/cm²) (x, y) (cd/m²) (cd/A) Light-emitting 4.30.29 7.2 (0.66, 0.34) 1011 14.0 element 1 Light-emitting 3.5 0.02 0.6(0.29, 0.70) 996 161.5 element 2 Light-emitting 3.3 0.92 23.1 (0.14,0.05) 1010 4.4 element 3

FIG. 50B shows emission spectra when a current at a current density of2.5 mA/cm² was supplied to the light-emitting elements 1 to 3. As shownin FIG. 50B, an emission spectrum of the light-emitting element 1 has apeak in the red wavelength range, an emission spectrum of thelight-emitting element 2 has a peak in the green wavelength range, andan emission spectrum of the light-emitting element 3 has a peak in theblue wavelength range. Note that as shown in Table 1, in each of thelight-emitting elements 1 to 3, the distance between the lower electrodeand the light-emitting layer was adjusted. Specifically, the distancebetween the lower electrode 504 of the light-emitting element 1 and thefirst light-emitting layer 510(1) of the light-emitting element 1 was190 nm, the distance between the lower electrode 504 of thelight-emitting element 2 and the first light-emitting layer 510(1) ofthe light-emitting element 2 was 155 nm, and the distance between thelower electrode 504 of the light-emitting element 3 and the secondlight-emitting layer 512 of the light-emitting element 3 was 132.5 nm.

As shown in Table 2, FIGS. 49A and 49B, and FIGS. 50A and 50B, thelight-emitting elements 1 to 3 each have element characteristics havinghigh efficiency and light emission in a desired wavelength range.Moreover, it is found that, in each of the light-emitting elements 1 and2, the guest material in the second light-emitting layer 512 does notcontribute to light emission regardless of the structures provided withthe second light-emitting layer 512.

The structure described in Example 1 can be combined with any of thestructures described in the other examples and the embodiments asappropriate.

Example 2

In Example 2, an example of fabricating a light-emitting element of oneembodiment of the present invention will be described. Note that inExample 2, a light-emitting element 4, a light-emitting element 5, and alight-emitting element 6 were fabricated.

Schematic cross-sectional views of the light-emitting elements 4 and 5are each in FIG. 48C, a schematic cross-sectional view of thelight-emitting element 6 is in FIG. 48D, and the detailed structures ofthe light-emitting elements 4 to 6 are shown in Table 3. Note thatstructures and abbreviations of the compounds used here are the same asthose in Example 1.

TABLE 3 Layer Reference numeral Thickness (nm) Material Weight ratioLight- Coloring layer 556 — Red*¹⁾ — emitting Upper electrode 514(2) 70ITO — element 4 514(1) 15 Ag:Mg 1:0.1*²⁾ Electron-injection 534 1 LiF —layer Electron- 533(2) 15 NBphen — transport layer 533(1) 5 cgDBCzPA —Second light- 512 25 cgDBCzPA:1,6BnfAPrn-03 1:0.05 emitting layer Firstlight-emitting 510(2) 15 2mDBTBPDBq-II:Ir(tBuppm)₂(acac) 1:0.06 layer510(1) 20 2mDBTBPDBq-II:PCBBiF:Ir(tBuppm)₂(acac) 0.8:0.2:0.06 Optical508 22.5 PCPPn — adjustment layer Hole-transport 532 22.5 PCPPn — layerHole-injection 531 35 PCPPn:MoO_(x) 2:1 layer Transparent 506 110 ITSO —conductive layer Lower electrode 504 100 APC — Light- Coloring layer 556— Green*¹⁾ — emitting Upper electrode 514(2) 70 ITO — element 5 514(1)15 Ag:Mg 1:0.1*²⁾ Electron-injection 534 1 LiF — layer Electron- 533(2)15 NBphen — transport layer 533(1) 5 cgDBCzPA — Second light- 512 25cgDBCzPA:1,6BnfAPrn-03 1:0.05 emitting layer First light-emitting 510(2)15 2mDBTBPDBq-II:Ir(tBuppm)₂(acac) 1:0.06 layer 510(1) 202mDBTBPDBq-II:PCBBiF:Ir(tBuppm)₂(acac) 0.8:0.2:0.06 Optical 508 22.5PCPPn — adjustment layer Hole-transport 532 22.5 PCPPn — layerHole-injection 531 25 PCPPn:MoO_(x) 2:1 layer Transparent 506 85 ITSO —conductive layer Lower electrode 504 100 APC — Light- Coloring layer 556— Blue*¹⁾ — emitting Upper electrode 514(2) 70 ITO — element 6 514(1) 15Ag:Mg 1:0.1*²⁾ Electron-injection 534 1 LiF — layer Electron- 533(2) 15NBphen — transport layer 533(1) 5 cgDBCzPA — Second light- 512 25cgDBCzPA:1,6BnfAPrn-03 1:0.05 emitting layer First light-emitting — — —— layer — — — — Optical — — — — adjustment layer Hole-transport 532 22.5PCPPn — layer Hole-injection 531 25 PCPPn:MoO_(x) 2:1 layer Transparent506 85 ITSO — conductive layer Lower electrode 504 100 APC — *¹⁾color*²⁾volume ratio<2-1. Fabrication of Light-Emitting Elements 4 to 6>

The light-emitting elements 4 and 5 are different from thelight-emitting elements 1 and 2 in Example 1 in the thickness of thefirst light-emitting layer 510(2). Note that the thickness of the firstlight-emitting layer 510(2) was 15 nm in each of the light-emittingelements 4 and 5. The light-emitting elements 5 and 6 were differentfrom the light-emitting elements 2 and 3 in Example 1 in the structureof the sealing substrate 550. Specifically, as illustrated in FIGS. 48Cand 48D and shown in Table 3, the sealing substrates 550 of thelight-emitting elements 5 and 6 are each provided with the coloringlayer 556. In Example 2, a green (G) color filter was formed as thecoloring layer 556 of the light-emitting element 5, and a blue (B) colorfilter was formed as the coloring layer 556 of the light-emittingelement 6.

Note that the structure of the light-emitting element 4 is differentfrom that of the light-emitting element 1 only in the firstlight-emitting layer 510(2), the structure of the light-emitting element5 is different from that of the light-emitting element 2 only in thefirst light-emitting layer 510(2) and the coloring layer 556, and thestructure of the light-emitting element 6 is different from that of thelight-emitting element 3 only in the coloring layer 556.

Each of the light-emitting elements over the substrate 502 fabricated asdescribed above was sealed by being bonded to the sealing substrate 550in a glove box in a nitrogen atmosphere so as not to be exposed to theair. Note that the sealing method was the same as that in Example 1.

Through the above process, the light-emitting elements 4 to 6 werefabricated.

Note that in all the above evaporation steps for the light-emittingelements 4 to 6, a resistive heating method was used as an evaporationmethod.

<2-2. Characteristics of Light-Emitting Elements 4 to 6>

FIGS. 51A, 51B, and 52A show luminance-current density characteristics,luminance-voltage characteristics, and current efficiency-luminancecharacteristics, respectively, of the light-emitting elements 4 to 6.Note that the measurements of the light-emitting elements were carriedout at room temperature (in an atmosphere kept at 25° C.).

Table 4 shows element characteristics of the light-emitting elements 4to 6 at around 1000 cd/m².

TABLE 4 Voltage Current Current density Chromaticity Luminance Currentefficiency (V) (mA) (mA/cm²) (x, y) (cd/m²) (cd/A) Light-emitting 4.40.29 7.2 (0.66, 0.34) 1044 14.5 element 4 Light-emitting 3.7 0.03 0.9(0.29, 0.70) 1097 126.3 element 5 Light-emitting 3.4 1.17 29.3 (0.14,0.04) 926 3.2 element 6

FIG. 52B shows emission spectra when a current at a current density of2.5 mA/cm² was supplied to the light-emitting elements 4 to 6. As shownin FIG. 52B, an emission spectrum of the light-emitting element 4 has apeak in the red wavelength range, an emission spectrum of thelight-emitting element 5 has a peak in the green wavelength range, andan emission spectrum of the light-emitting element 6 has a peak in theblue wavelength range.

As shown in Table 4, FIGS. 51A and 51B, and FIGS. 52A and 52B, thelight-emitting elements 4 to 6 each have element characteristics havinghigh efficiency and light emission in a desired wavelength range. Sincethe light-emitting elements 5 and 6 are each provided with the coloringlayer 556, they have higher color purity than the light-emittingelements 2 and 3 in Example 1.

The structure described in Example 2 can be combined with any of thestructures described in the other examples and the embodiments asappropriate.

Example 3

In Example 3, an example of fabricating a light-emitting element of oneembodiment of the present invention will be described. Note that inExample 3, a light-emitting element 7, a light-emitting element 8, and alight-emitting element 9 were fabricated.

Schematic cross-sectional views of the light-emitting elements 7 and 8are each in FIG. 48C, a schematic cross-sectional view of thelight-emitting element 9 is in FIG. 48D, and the detailed structures ofthe light-emitting elements 7 to 9 are shown in Table 5. Note thatstructures and abbreviations of the compounds used here are given below,and compounds other than those given below are the same as those inExample 1 and Example 2.

TABLE 5 Layer Reference numeral Thickness (nm) Material Weight ratioLight- Coloring layer 556 — Red*¹⁾ — emitting Upper electrode 514(2) 70ITO — element 7 514(1) 15 Ag:Mg 1:0.1*²⁾ Electron-injection 534 1 LiF —layer Electron- 533(2) 15 NBphen — transport layer 533(1) 5 cgDBCzPA —Second light- 512 25 cgDBCzPA:1,6BnfAPrn-03 1:0.03 emitting layer Firstlight-emitting 510(2) 15 2mDBTBPDBq-II:Ir(iBu5bpm)₂(acac) 1:0.04 layer510(1) 20 2mDBTBPDBq-II:PCBBiF:Ir(iBu5bpm)₂(acac) 0.8:0.2:0.04 Optical508 25 PCBBiF — adjustment layer Hole-transport 532 15 PCPPn — layerHole-injection 531 40 PCPPn:MoO_(x) 2:1 layer Transparent 506 110 ITSO —conductive layer Lower electrode 504 100 APC — Light- Coloring layer 556— Green*¹⁾ — emitting Upper electrode 514(2) 70 ITO — element 8 514(1)15 Ag:Mg 1:0.1*²⁾ Electron-injection 534 1 LiF — layer Electron- 533(2)15 NBphen — transport layer 533(1) 5 cgDBCzPA — Second light- 512 25cgDBCzPA:1,6BnfAPrn-03 1:0.03 emitting layer First light-emitting 510(2)15 2mDBTBPDBq-II:Ir(iBu5bpm)₂(acac) 1:0.04 layer 510(1) 202mDBTBPDBq-II:PCBBiF:Ir(iBu5bpm)₂(acac) 0.8:0.2:0.04 Optical 508 25PCBBiF — adjustment layer Hole-transport 532 15 PCPPn — layerHole-injection 531 30 PCPPn:MoO_(x) 2:1 layer Transparent 506 85 ITSO —conductive layer Lower electrode 504 100 APC — Light- Coloring layer 556— Blue*¹⁾ — emitting Upper electrode 514(2) 70 ITO — element 9 514(1) 15Ag:Mg 1:0.1*²⁾ Electron-injection 534 1 LiF — layer Electron- 533(2) 15NBphen — transport layer 533(1) 5 cgDBCzPA — Second light- 512 25cgDBCzPA:1,6BnfAPrn-03 1:0.03 emitting layer First light-emitting — — —— layer — — — — Optical — — — — adjustment layer Hole-transport 532 15PCPPn — layer Hole-injection 531 30 PCPPn:MoO_(x) 2:1 layer Transparent506 85 ITSO — conductive layer Lower electrode 504 100 APC — *¹⁾color*²⁾volume ratio<3-1. Fabrication of Light-Emitting Elements 7 and 8>

First, over the substrate 502, APC was formed as the lower electrode 504by a sputtering method. Note that the thickness of the lower electrode504 was 100 nm and the area of the lower electrode 504 was 4 mm² (2 mm×2mm).

Then, over the lower electrode 504, ITSO was deposited as thetransparent conductive layer 506 by a sputtering method. Note that thethickness of the transparent conductive layer 506 was 110 nm in thelight-emitting element 7, and the thickness of the transparentconductive layer 506 was 85 nm in the light-emitting element 8.

Then, as pretreatment of evaporation of an organic compound layer, thetransparent conductive layer 506 side of the substrate 502 provided withthe lower electrode 504 and the transparent conductive layer 506 waswashed with water, baking was performed at 200° C. for one hour, andthen UV ozone treatment was performed on a surface of the transparentconductive layer 506 for 370 seconds.

After that, the substrate 502 was transferred into a vacuum evaporationapparatus where the pressure had been reduced to approximately 10⁻⁴ Pa,and was subjected to vacuum baking at 170° C. for 60 minutes in aheating chamber of the vacuum evaporation apparatus, and then thesubstrate 502 was cooled down for about 30 minutes.

Then, the substrate 502 was fixed to a holder provided in the vacuumevaporation apparatus so that a surface of the substrate 502 over whichthe transparent conductive layer 506 was formed faced downward. InExample 3, by a vacuum evaporation method, the hole-injection layer 531,the hole-transport layer 532, the optical adjustment layer 508, thefirst light-emitting layer 510(1), the first light-emitting layer510(2), the second light-emitting layer 512, the electron-transportlayer 533(1), the electron-transport layer 533(2), theelectron-injection layer 534, the upper electrode 514(1), and the upperelectrode 514(2) were sequentially formed. The fabrication method isdescribed in detail below.

First, the pressure in the vacuum evaporation apparatus was reduced to10⁻⁴ Pa. Then, on the transparent conductive layer 506, thehole-injection layer 531 was formed by co-evaporation of PCPPn andmolybdenum oxide at a weight ratio of 2:1 (PcPPn:molybdenum oxide). Notethat the thickness of the hole-injection layer 531 was 40 nm in thelight-emitting element 7, and the thickness of the hole-injection layer531 was 30 nm in the light-emitting element 8.

Then, the hole-transport layer 532 was formed on the hole-injectionlayer 531. As the hole-transport layer 532, PCPPn was evaporated. Notethat the thickness of the hole-transport layer 532 was 15 nm.

Then, the optical adjustment layer 508 was formed on the hole-transportlayer 532. As the optical adjustment layer 508, PCBBiF was evaporated.Note that the thickness of the optical adjustment layer 508 was 25 nm.

Then, the first light-emitting layer 510(1) was formed on the opticaladjustment layer 508. The first light-emitting layer 510(1) was formedby co-evaporation of 2mDBTBPDBq-II, PCBBiF, and bis{3-[6-isobutyl-4-pyrimidinyl-κN3]biphenyl-κC4}(2,4-pentanedionato-κ²O,O′)iridium(III) (abbreviation: Ir(iBu5bpm)₂(acac)) at a weight ratio of0.8:0.2:0.04 (2mDBTBPDBq-II:PCBBiF: Ir(iBu5bpm)₂(acac)). Note that thethickness of the first light-emitting layer 510(1) was 20 nm. Note that2mDBTBPDBq-II was the host material, PCBBiF was the assist material, andIr(iBu5bpm)₂(acac) was the phosphorescent material (the guest material)in the first light-emitting layer 510(1).

Note that although Ir(iBu5bpm)₂(acac) was used as the phosphorescentmaterial in Example 3, a different phosphorescent material may be usedwithout limitation thereto. For example, Ir(mppm)₂(acac),Ir(tBuppm)₂(acac), or the like can be used. The chemical formulae ofIr(mppm)₂(acac) and Ir(tBuppm)₂(acac) are shown below.

Ir(mppm)₂(acac) includes a phenyl group at the 4-position of apyrimidine ring coordinated to iridium metal and a methyl group at the6-position of the pyrimidine ring coordinated to the iridium metal.Ir(tBuppm)₂(acac) includes a phenyl group at the 4-position of apyrimidine ring coordinated to iridium metal and a tert-butyl group atthe 6-position of the pyrimidine ring coordinated to the iridium metal.In contrast, Ir(iBu5bpm)₂(acac) used in Example 3 includes a biphenylgroup at the 4-position of a pyrimidine ring coordinated to iridiummetal and an isobutyl group at the 6-position of the pyrimidine ringcoordinated to the iridium metal.

Note that Ir(iBu5bpm)₂(acac), a novel compound, is preferably used as aphosphorescent material as in the light-emitting elements fabricated inExample 3 because emission efficiency can be in some cases higher thanthat of a light-emitting element in which, for example, Ir(mppm)₂(acac)is used as a phosphorescent material. Ir(iBu5bpm)₂(acac) is preferablyused because it has the biphenyl group instead of the phenyl groupunlike Ir(mppm)₂(acac) and Ir(tBuppm)₂(acac), and a long lifetime can beachieved in some cases. Furthermore, Ir(iBu5bpm)₂(acac) is preferablyused as the light-emitting material used in the light-emitting elementof one embodiment of the present invention because it has spectrumcomponents of green light and red light.

Then, the first light-emitting layer 510(2) was formed on the firstlight-emitting layer 510(1). Then, the first light-emitting layer 510(2)was formed by co-evaporation of 2mDBTBPDBq-II and Ir(iBu5bpm)₂(acac) ata weight ratio of 1:0.04 (2mDBTBPDBq-II: Ir(iBu5bpm)₂(acac)). Note thatthe thickness of the first light-emitting layer 510(2) was 15 nm. Notethat 2mDBTBPDBq-II was the host material and Ir(iBu5bpm)₂(acac) was thephosphorescent material (the guest material) in the first light-emittinglayer 510(2).

Then, the second light-emitting layer 512 was formed on the firstlight-emitting layer 510(2). The second light-emitting layer 512 wasformed by co-evaporation of cgDBCzPA and 1,6BnfAPrn-03 at a weight ratioof 1:0.03 (cgDBCzPA: 1,6BnfAPrn-03). Note that the thickness of thesecond light-emitting layer 512 was 25 nm. Note that cgDBCzPA was thehost material and 1,6BnfAPm-03 was the fluorescent material (the guestmaterial) in the second light-emitting layer 512.

Then, on the second light-emitting layer 512, the electron-transportlayer 533(1) was formed by evaporation of cgDBCzPA to a thickness of 5nm. Then, on the electron-transport layer 533(1), the electron-transportlayer 533(2) was formed by evaporation of NBphen to a thickness of 15nm. Then, on the electron-transport layer 533(2), the electron-injectionlayer 534 was formed by evaporation of LiF to a thickness of 1 nm.

Then, on the electron-injection layer 534, the upper electrode 514(1)was formed by co-evaporation of Ag and Mg at a volume ratio of 1:0.1.Note that the thickness of the upper electrode 514(1) was 15 nm. Then,on the upper electrode 514(1), ITO was deposited as the upper electrode514(2) by a sputtering method to a thickness of 70 nm.

Next, the sealing substrate 550 was prepared. Note that as illustratedin FIG. 48C and shown in Table 4, the sealing substrates 550 of thelight-emitting elements 7 and 8 are each provided with the coloringlayer 556. In Example 3, a red (R) color filter was formed as thecoloring layer 556 of the light-emitting element 7, and a green (G)color filter was formed as the coloring layer 556 of the light-emittingelement 8.

Each of the light-emitting elements over the substrate 502 fabricated asdescribed above was sealed by being bonded to the sealing substrate 550in a glove box in a nitrogen atmosphere so as not to be exposed to theair. Note that the sealing method was the same as that in Example 1.

Through the above process, the light-emitting elements 7 and 8 werefabricated.

<3-2. Fabrication of Light-Emitting Element 9>

First, over the substrate 502, APC was formed as the lower electrode 504by a sputtering method. Note that the thickness of the lower electrode504 was 100 nm and the area of the lower electrode 504 was 4 mm².

Then, over the lower electrode 504, ITSO was deposited as thetransparent conductive layer 506 by a sputtering method. Note that thethickness of the transparent conductive layer 506 was 85 nm.

Then, as pretreatment of evaporation of an organic compound layer, thetransparent conductive layer 506 side of the substrate 502 provided withthe lower electrode 504 and the transparent conductive layer 506 waswashed with water, baking was performed at 200° C. for one hour, andthen UV ozone treatment was performed on a surface of the transparentconductive layer 506 for 370 seconds.

After that, the substrate 502 was transferred into a vacuum evaporationapparatus where the pressure had been reduced to approximately 10⁻⁴ Pa,and was subjected to vacuum baking at 170° C. for 60 minutes in aheating chamber of the vacuum evaporation apparatus, and then thesubstrate 502 was cooled down for about 30 minutes.

Then, the substrate 502 was fixed to a holder provided in the vacuumevaporation apparatus so that a surface of the substrate 502 over whichthe transparent conductive layer 506 was formed faced downward. InExample 3, by a vacuum evaporation method, the hole-injection layer 531,the hole-transport layer 532, the second light-emitting layer 512, theelectron-transport layer 533(1), the electron-transport layer 533(2),the electron-injection layer 534, the upper electrode 514(1), and theupper electrode 514(2) were sequentially formed. That is, the opticaladjustment layer 508, the first light-emitting layer 510(1), and thefirst light-emitting layer 510(2) are not formed in the light-emittingelement 9, unlike in the light-emitting elements 7 and 8. Thefabrication method is described in detail below.

First, the pressure in the vacuum evaporation apparatus was reduced to10⁻⁴ Pa. Then, on the transparent conductive layer 506, thehole-injection layer 531 was forming by co-evaporation of PCPPn andmolybdenum oxide at a weight ratio of 2:1 (PcPPn:molybdenum oxide). Notethat the thickness of the hole-injection layer 531 was 30 nm.

Then, the hole-transport layer 532 was formed on the hole-injectionlayer 531. As the hole-transport layer 532, PCPPn was evaporated. Notethat the thickness of the hole-transport layer 532 was 15 nm.

Then, the second light-emitting layer 512 was formed on thehole-transport layer 532. The second light-emitting layer 512 was formedby co-evaporation of cgDBCzPA and 1,6BnfAPrn-03 at a weight ratio of1:0.03 (cgDBCzPA: 1,6BnfAPm-03). Note that the thickness of the secondlight-emitting layer 512 was 25 nm.

Then, on the second light-emitting layer 512, the electron-transportlayer 533(1) was formed by evaporation of cgDBCzPA to a thickness of 5nm. Then, on the electron-transport layer 533(1), the electron-transportlayer 533(2) was formed by evaporation of NBphen to a thickness of 15nm. Then, on the electron-transport layer 533(2), the electron-injectionlayer 534 was formed by evaporation of LiF to a thickness of 1 nm.

Then, on the electron-injection layer 534, the upper electrode 514(1)was formed by co-evaporation of Ag and Mg at a volume ratio of 1:0.1.Note that the thickness of the upper electrode 514(1) was 15 nm. Then,on the upper electrode 514(1), ITO was deposited as the upper electrode514(2) by a sputtering method to a thickness of 70 nm.

Next, the sealing substrate 550 was prepared.

Note that as illustrated in FIG. 48D and shown in Table 5, the sealingsubstrate 550 of the light-emitting element 9 is provided with thecoloring layer 556. In Example 3, a red (R) color filter was formed asthe coloring layer 556 of the light-emitting element 9.

The light-emitting element over the substrate 502 fabricated asdescribed above was sealed by being bonded to the sealing substrate 550in a glove box in a nitrogen atmosphere so as not to be exposed to theair. Note that the sealing method was the same as those of thelight-emitting elements 7 and 8.

Through the above process, the light-emitting element 9 was fabricated.

Note that in all the above evaporation steps for the light-emittingelements 7 to 9, a resistive heating method was used as an evaporationmethod.

<3-3. Characteristics of Light-Emitting Elements 7 to 9>

FIGS. 53A, 53B, and 54A show luminance-current density characteristics,luminance-voltage characteristics, and current efficiency-luminancecharacteristics, respectively, of the light-emitting elements 7 to 9.Note that the measurements of the light-emitting elements were carriedout at room temperature (in an atmosphere kept at 25° C.).

Table 6 shows element characteristics of the light-emitting elements 7to 9 at around 1000 cd/m².

TABLE 6 Voltage Current Current density Chromaticity Luminance Currentefficiency (V) (mA) (mA/cm²) (x, y) (cd/m²) (cd/A) Light-emitting 3.80.22 5.4 (0.66, 0.34) 965 17.8 element 7 Light-emitting 3.3 0.03 0.8(0.31, 0.68) 898 107.6 element 8 Light-emitting 3.4 1.18 29.5 (0.14,0.04) 967 3.3 element 9

FIG. 54B shows emission spectra when a current at a current density of2.5 mA/cm² was supplied to the light-emitting elements 7 to 9. As shownin FIG. 54B, an emission spectrum of the light-emitting element 7 has apeak in the red wavelength range, an emission spectrum of thelight-emitting element 8 has a peak in the green wavelength range, andan emission spectrum of the light-emitting element 9 has a peak in theblue wavelength range. Note that as shown in Table 5, in each of thelight-emitting elements 7 to 9, the distance between the lower electrodeand the light-emitting layer was adjusted. Specifically, the distancebetween the lower electrode 504 of the light-emitting element 7 and thefirst light-emitting layer 510(1) of the light-emitting element 7 was190 nm, the distance between the lower electrode 504 of thelight-emitting element 8 and the first light-emitting layer 510(1) ofthe light-emitting element 8 was 155 nm, and the distance between thelower electrode 504 of the light-emitting element 9 and the secondlight-emitting layer 512 of the light-emitting element 9 was 130 nm.

As shown in Table 6, FIGS. 53A and 53B, and FIGS. 54A and 54B, thelight-emitting elements 7 to 9 each have element characteristics havinghigh efficiency and light emission in a desired wavelength range.Moreover, it is found that, in each of the light-emitting elements 7 and8, the guest material in the second light-emitting layer 512 does notcontribute to light emission regardless of the structures provided withthe second light-emitting layer 512.

Next, a reliability test was performed on each of the light-emittingelements 7 to 9. FIG. 55 shows results of the reliability tests.

In the reliability test, each of the light-emitting elements 7 to 9 wasdriven under the conditions where the initial luminance was 5000 cd/m²and the current density was constant. In FIG. 55, The vertical axisrepresents normalized luminance (%) with the initial luminance of 100%,and the horizontal axis represents driving time (h) of the element. Theresults in FIG. 55 indicate that the normalized luminance of thelight-emitting element 7 after 1074 hours was 89%, the normalizedluminance of the light-emitting element 8 after 1074 hours was 95%, andthe normalized luminance of the light-emitting element 9 after 1642hours was 91%.

The results in FIGS. 53A and 53B, FIGS. 54A and 54B, and FIG. 55indicate that the light-emitting elements 7 to 9, each of which is oneembodiment of the present invention, have excellent elementcharacteristics (voltage-luminance characteristics, luminance-currentefficiency characteristics, and voltage-current characteristics) andhigh reliability (normalized luminance-time characteristics).

The structure described in Example 3 can be combined with any of thestructures described in the other examples and the embodiments asappropriate.

Reference Example 1

Light-emitting elements (a light-emitting element 10, a light-emittingelement 11, and a light-emitting element 12) in modes different fromthose of the light-emitting elements described in Examples 1 to 3 werefabricated and evaluated below.

A schematic cross-sectional view of the light-emitting element 10 is inFIG. 56C, a schematic cross-sectional view of the light-emitting element11 is in FIG. 56A, a schematic cross-sectional view of thelight-emitting element 12 is in FIG. 56B, the detailed structures of thelight-emitting elements 10 to 12 are shown in Table 7. Note thatstructures and abbreviations of the compounds used here are given below,and compounds other than those given below are the same as those inExample 1.

TABLE 7 Layer Reference numeral Thickness (nm) Material Weight ratioLight- Coloring layer 556 — Red*¹⁾ — emitting Upper electrode 514(2) 70ITO — element 10 514(1) 15 Ag:Mg 1:0.1*²⁾ Electron-injection 534 1 LiF —layer Electron- 533(2) 15 NBphen — transport layer 533(1) 5 cgDBCzPA —Second light- 512 25 cgDBCzPA:1,6BnfAPrn-03 1:0.05 emitting layer Firstlight-emitting 510 25 2mDBTBPDBq-II:PCBBiF:Ir(tBuppm)₂(acac)0.8:0.2:0.06 layer Optical 508 20 BPAFLP — adjustment layerHole-transport 532 15 PCPPn — layer Hole-injection 531 55 PCPPn:MoO_(x)2:1 layer Transparent 506 110 ITSO — conductive layer Lower electrode504 100 APC — Light- Upper electrode 514(2) 70 ITO — emitting 514(1) 15Ag:Mg 1:0.1*²⁾ element 11 Electron-injection 534 1 LiF — layer Electron-533(2) 15 NBphen — transport layer 533(1) 5 cgDBCzPA — Second light- 51225 cgDBCzPA:1,6BnfAPrn-03 1:0.05 emitting layer First light-emitting 51025 2mDBTBPDBq-II:PCBBiF:Ir(tBuppm)₂(acac) 0.8:0.2:0.06 layer Optical 50820 BPAFLP — adjustment layer Hole-transport 532 15 PCPPn — layerHole-injection 531 45 PCPPn:MoO_(x) 2:1 layer Transparent 506 85 ITSO —conductive layer Lower electrode 504 100 APC — Light- Upper electrode514(2) 70 ITO — emitting Electron-injection 514(1) 15 Ag:Mg 1:0.1*²⁾element 12 layer 534 1 LiF — Electron- 533(2) 15 NBphen — transportlayer 533(1) 5 cgDBCzPA — Second light- 512 25 cgDBCzPA:1,6BnfAPrn-031:0.05 emitting layer First light-emitting — — — — layer Optical — — — —adjustment layer Hole-transport 532 15 PCPPn — layer Hole-injection 531102.5 PCPPn:MoO_(x) 2:1 layer Transparent 506 10 ITSO — conductive layerLower electrode 504 100 APC — *¹⁾color *²⁾volume ratio<4-1. Fabrication of Light-Emitting Elements 10 and 11>

First, over the substrate 502, APC was formed as the lower electrode 504by a sputtering method. Note that the thickness of the lower electrode504 was 100 nm and the area of the lower electrode 504 was 4 mm² (2 mm×2mm).

Then, over the lower electrode 504, ITSO was deposited as thetransparent conductive layer 506 by a sputtering method. Note that thethickness of the transparent conductive layer 506 was 110 nm in thelight-emitting element 10, and the thickness of the transparentconductive layer 506 was 85 nm in the light-emitting element 11.

Then, as pretreatment of evaporation of an organic compound layer, thetransparent conductive layer 506 side of the substrate 502 provided withthe lower electrode 504 and the transparent conductive layer 506 waswashed with water, baking was performed at 200° C. for one hour, andthen UV ozone treatment was performed on a surface of the transparentconductive layer 506 for 370 seconds.

After that, the substrate 502 was transferred into a vacuum evaporationapparatus where the pressure had been reduced to approximately 10⁻⁴ Pa,and was subjected to vacuum baking at 170° C. for 60 minutes in aheating chamber of the vacuum evaporation apparatus, and then thesubstrate 502 was cooled down for about 30 minutes.

Then, the substrate 502 was fixed to a holder provided in the vacuumevaporation apparatus so that a surface of the substrate 502 over whichthe transparent conductive layer 506 was formed faced downward. InReference Example 1, by a vacuum evaporation method, the hole-injectionlayer 531, the hole-transport layer 532, the optical adjustment layer508, the first light-emitting layer 510, the second light-emitting layer512, the electron-transport layer 533(1), the electron-transport layer533(2), the electron-injection layer 534, the upper electrode 514(1),and the upper electrode 514(2) were sequentially formed. The fabricationmethod is described in detail below.

First, the pressure in the vacuum evaporation apparatus was reduced to10⁻⁴ Pa. Then, on the transparent conductive layer 506, thehole-injection layer 531 was formed by co-evaporation of PCPPn andmolybdenum oxide at a weight ratio of 2:1 (PcPPn:molybdenum oxide). Notethat the thickness of the hole-injection layer 531 was 55 nm in thelight-emitting element 10, and the thickness of the hole-injection layer531 was 45 nm in the light-emitting element 11.

Then, the hole-transport layer 532 was formed on the hole-injectionlayer 531. As the hole-transport layer 532, PCPPn was evaporated. Notethat the thickness of the hole-transport layer 532 was 15 nm.

Then, the optical adjustment layer 508 was formed on the hole-transportlayer 532. As the optical adjustment layer 508,4-phenyl-4′-(9-phenylfluoren-9-yl)triphenylamin (abbreviation: BPAFLP)was evaporated to a thickness of 20 nm.

Then, the first light-emitting layer 510 was formed on the opticaladjustment layer 508. The first light-emitting layer 510 was formed byco-evaporation of 2mDBTBPDBq-II, PCBBiF, and Ir(tBuppm)₂(acac) at aweight ratio of 0.8:0.2:0.06 (2mDBTBPDBq-II:PCBBiF: Ir(tBuppm)₂(acac)).Note that the thickness of the first light-emitting layer 510 was 25 nm.Note that 2mDBTBPDBq-II was the host material, PCBBiF was the assistmaterial, and Ir(tBuppm)₂(acac) was the phosphorescent material (theguest material) in the first light-emitting layer 510.

Then, the second light-emitting layer 512 was formed on the firstlight-emitting layer 510. The second light-emitting layer 512 was formedby co-evaporation of cgDBCzPA and 1,6BnfAPm-03 at a weight ratio of1:0.05 (cgDBCzPA: 1,6BnfAPm-03). Note that the thickness of the secondlight-emitting layer 512 was 25 mm. Note that cgDBCzPA was the hostmaterial and 1,6BnfAPrn-03 was the fluorescent material the guestmaterial) in the second light-emitting layer 512.

Then, on the second light-emitting layer 512, the electron-transportlayer 533(1) was formed by evaporation of cgDBCzPA to a thickness of 5nm. Then, on the electron-transport layer 533(1), the electron-transportlayer 533(2) was formed by evaporation of NBphen to a thickness of 15nm. Then, on the electron-transport layer 533(2), the electron-injectionlayer 534 was formed by evaporation of LiF to a thickness of 1 nm.

Then, on the electron-injection layer 534, the upper electrode 514(1)was formed by co-evaporation of Ag and Mg at a volume ratio of 1:0.1.Note that the thickness of the upper electrode 514(1) was 15 nm. Then,on the upper electrode 514(1), ITO was deposited as the upper electrode514(2) by a sputtering method to a thickness of 70 nm.

Next, the sealing substrate 550 was prepared. Note that as illustratedin FIG. 56C and shown in Table 7, the sealing substrate 550 of thelight-emitting element 10 is provided with the coloring layer 556. InReference Example 1, a red (R) color filter was formed as the coloringlayer 556.

Each of the light-emitting elements over the substrate 502 fabricated asdescribed above was sealed by being bonded to the sealing substrate 550in a glove box in a nitrogen atmosphere so as not to be exposed to theair. Note that the sealing method was the same as that in Example 1.

Through the above process, the light-emitting elements 10 and 11 werefabricated.

<4-2. Fabrication of Light-Emitting Element 12>

First, over the substrate 502, APC was formed as the lower electrode 504by a sputtering method. Note that the thickness of the lower electrode504 was 100 nm and the area of the lower electrode 504 was 4 mm² (2 mm×2mm).

Then, over the lower electrode 504, ITSO was deposited as thetransparent conductive layer 506 by a sputtering method. Note that thethickness of the transparent conductive layer 506 was 10 nm.

Then, as pretreatment of evaporation of an organic compound layer, thetransparent conductive layer 506 side of the substrate 502 provided withthe lower electrode 504 and the transparent conductive layer 506 waswashed with water, baking was performed at 200° C. for one hour, andthen UV ozone treatment was performed on a surface of the transparentconductive layer 506 for 370 seconds.

After that, the substrate 502 was transferred into a vacuum evaporationapparatus where the pressure had been reduced to approximately 10⁻⁴ Pa,and was subjected to vacuum baking at 170° C. for 60 minutes in aheating chamber of the vacuum evaporation apparatus, and then thesubstrate 502 was cooled down for about 30 minutes.

Then, the substrate 502 was fixed to a holder provided in the vacuumevaporation apparatus so that a surface of the substrate 502 over whichthe transparent conductive layer 506 was formed faced downward. InReference Example 1, by a vacuum evaporation method, the hole-injectionlayer 531, the hole-transport layer 532, the second light-emitting layer512, the electron-transport layer 533(1), the electron-transport layer533(2), the electron-injection layer 534, the upper electrode 514(1),and the upper electrode 514(2) were sequentially formed. That is, theoptical adjustment layer 508 and the first light-emitting layer 510 arenot formed, unlike in the light-emitting elements 10 and 11. Thefabrication method is described in detail below.

First, the pressure in the vacuum evaporation apparatus was reduced to10⁻⁴ Pa. Then, on the transparent conductive layer 506, thehole-injection layer 531 was formed by co-evaporation of PCPPn andmolybdenum oxide at a weight ratio of 2:1 (PcPPn:molybdenum oxide). Notethat the thickness of the hole-injection layer 531 was 102.5 nm.

Then, the hole-transport layer 532 was formed on the hole-injectionlayer 531. As the hole-transport layer 532, PCPPn was evaporated. Notethat the thickness of the hole-transport layer 532 was 15 nm.

Then, the second light-emitting layer 512 was formed on thehole-transport layer 532. The second light-emitting layer 512 was formedby co-evaporation of cgDBCzPA and 1,6BnfAPrn-03 at a weight ratio of1:0.05 (cgDBCzPA: 1,6BnfAPrn-03). Note that the thickness of the secondlight-emitting layer 512 was 25 nm.

Then, on the second light-emitting layer 512, the electron-transportlayer 533(1) was formed by evaporation of cgDBCzPA to a thickness of 5nm. Then, on the electron-transport layer 533(1), the electron-transportlayer 533(2) was formed by evaporation of NBphen to a thickness of 15nm. Then, on the electron-transport layer 533(2), the electron-injectionlayer 534 was formed by evaporation of LiF to a thickness of 1 nm.

Then, on the electron-injection layer 534, the upper electrode 514(1)was formed by co-evaporation of Ag and Mg at a volume ratio of 1:0.1.Note that the thickness of the upper electrode 514(1) was 15 nm. Then,on the upper electrode 514(1), ITO was deposited as the upper electrode514(2) by a sputtering method to a thickness of 70 nm.

Next, the sealing substrate 550 was prepared.

The light-emitting element over the substrate 502 fabricated asdescribed above was sealed by being bonded to the sealing substrate 550in a glove box in a nitrogen atmosphere so as not to be exposed to theair. Note that the sealing method was the same as that in Example 1.

Through the above process, the light-emitting element 12 was fabricated.

Note that in all the above evaporation steps for the light-emittingelements 10 to 12, a resistive heating method was used as an evaporationmethod.

<4-3. Characteristics of Light-Emitting Elements 10 to 12>

FIGS. 57A, 57B, and 58A show luminance-current density characteristics,luminance-voltage characteristics, and current efficiency-luminancecharacteristics, respectively, of the light-emitting elements 10 to 12.Note that the measurements of the light-emitting elements were carriedout at room temperature (in an atmosphere kept at 25° C.).

Table 8 shows element characteristics of the light-emitting elements 10to 12 at around 1000 cd/m².

TABLE 8 Voltage Current Current density Chromaticity Luminance Currentefficiency (V) (mA) (mA/cm²) (x, y) (cd/m²) (cd/A) Light-emitting 4.00.30 7.6 (0.67, 0.33) 903 11.9 element 10 Light-emitting 3.5 0.04 1.0(0.28, 0.67) 984 100.6 element 11 Light-emitting 3.3 1.06 26.5 (0.14,0.05) 1082 4.1 element 12

FIG. 58B shows emission spectra when a current at a current density of2.5 mA/cm² was supplied to the light-emitting elements 10 to 12. Asshown in FIG. 58B, an emission spectrum of the light-emitting element 10has a peak in the red wavelength range, an emission spectrum of thelight-emitting element 11 has a peak in the green wavelength range, andan emission spectrum of the light-emitting element 12 has a peak in theblue wavelength range. Note that as shown in Table 7, in each of thelight-emitting elements 10 to 12, the distance between the lowerelectrode and the light-emitting layer was adjusted. Specifically, thedistance between the lower electrode 504 of the light-emitting element10 and the first light-emitting layer 510 of the light-emitting element10 was 200 nm, the distance between the lower electrode 504 of thelight-emitting element 11 and the first light-emitting layer 510 of thelight-emitting element 11 was 165 nm, and the distance between the lowerelectrode 504 of the light-emitting element 12 and the secondlight-emitting layer 512 of the light-emitting element 12 was 127.5 nm.

As shown in Table 8, FIGS. 57A and 57B, and FIGS. 58A and 58B, thelight-emitting elements 10 to 12 each have element characteristicshaving high efficiency and light emission in a desired wavelength range.Moreover, it is found that, in each of the light-emitting elements 10and 11, the guest material in the second light-emitting layer 512 doesnot contribute to light emission regardless of the structures providedwith the second light-emitting layer 512.

Reference Example 2

Light-emitting elements (a light-emitting element 13, a light-emittingelement 14, and a light-emitting element 15) in modes different fromthose of the light-emitting elements described in Examples 1 to 3 andReference Example 1 were fabricated and evaluated below. Note that thelight-emitting element 13 is the same as the light-emitting element 10described in Reference Example 1. Therefore, the fabrication method ofthe light-emitting element 13 is not described.

Schematic cross-sectional views of the light-emitting elements 13 and 14are each in FIG. 56C, a schematic cross-sectional view of thelight-emitting element 15 is in FIG. 56D, and the detailed structures ofthe light-emitting elements 13 to 15 are shown in Table 9. Note that thecompounds used here are the same as those used in Reference Example 1.

TABLE 9 Layer Reference numeral Thickness (nm) Material Weight ratioLight- Coloring layer 556 — Red*¹⁾ — emitting Upper electrode 514(2) 70ITO — element 13 514(1) 15 Ag:Mg 1:0.1*²⁾ Electron-injection 534 1 LiF —layer Electron- 533(2) 15 NBphen — transport layer 533(1) 5 cgDBCzPA —Second light- 512 25 cgDBCzPA:1,6BnfAPrn-03 1:0.05 emitting layer Firstlight-emitting 510 25 2mDBTBPDBq-II:PCBBiF:Ir(tBuppm)₂(acac)0.8:0.2:0.06 layer Optical 508 20 BPAFLP — adjustment layerHole-transport 532 15 PCPPn — layer Hole-injection 531 55 PCPPn:MoO_(x)2:1 layer Transparent 506 110 ITSO — conductive layer Lower electrode504 100 APC — Light- Coloring layer 556 — Green*¹⁾ — emitting Upperelectrode 514(2) 70 ITO — element 14 514(1) 15 Ag:Mg 1:0.1*²⁾Electron-injection 534 1 LiF — layer Electron- 533(2) 15 NBphen —transport layer 533(1) 5 cgDBCzPA — Second light- 512 25cgDBCzPA:1,6BnfAPrn-03 1:0.05 emitting layer First light-emitting 510 252mDBTBPDBq-II:PCBBiF:Ir(tBuppm)₂(acac) 0.8:0.2:0.06 layer Optical 508 20BPAFLP — adjustment layer Hole-transport 532 15 PCPPn — layerHole-injection 531 40 PCPPn:MoO_(x) 2:1 layer Transparent 506 85 ITSO —conductive layer Lower electrode 504 100 APC — Light- Coloring layer 556— Blue*¹⁾ — emitting Upper electrode 514(2) 70 ITO — element 15Electron-injection 514(1) 15 Ag:Mg 1:0.1*²⁾ layer 534 1 LiF — Electron-533(2) 15 NBphen — transport layer 533(1) 5 cgDBCzPA — Second light- 51225 cgDBCzPA:1,6BnfAPrn-03 1:0.05 emitting layer First light-emitting — —— — layer Optical — — — — adjustment layer Hole-transport 532 15 PCPPn —layer Hole-injection 531 102.5 PCPPn:MoO_(x) 2:1 layer Transparent 50610 ITSO — conductive layer Lower electrode 504 100 APC — *¹⁾color*²⁾volume ratio<5-1. Fabrication of Light-Emitting Elements 13 and 14>

First, over the substrate 502, APC was formed as the lower electrode 504by a sputtering method. Note that the thickness of the lower electrode504 was 100 nm and the area of the lower electrode 504 was 4 mm² (2 mm×2mm).

Then, over the lower electrode 504, ITSO was deposited as thetransparent conductive layer 506 by a sputtering method. Note that thethickness of the transparent conductive layer 506 was 110 nm in thelight-emitting element 13, and the thickness of the transparentconductive layer 506 was 85 nm in the light-emitting element 14.

Then, as pretreatment of evaporation of an organic compound layer, thetransparent conductive layer 506 side of the substrate 502 provided withthe lower electrode 504 and the transparent conductive layer 506 waswashed with water, baking was performed at 200° C. for one hour, andthen UV ozone treatment was performed on a surface of the transparentconductive layer 506 for 370 seconds.

After that, the substrate 502 was transferred into a vacuum evaporationapparatus where the pressure had been reduced to approximately 10⁻⁴ Pa,and was subjected to vacuum baking at 170° C. for 60 minutes in aheating chamber of the vacuum evaporation apparatus, and then thesubstrate 502 was cooled down for about 30 minutes.

Then, the substrate 502 was fixed to a holder provided in the vacuumevaporation apparatus so that a surface of the substrate 502 over whichthe transparent conductive layer 506 was formed faced downward. InReference Example 2, by a vacuum evaporation method, the hole-injectionlayer 531, the hole-transport layer 532, the optical adjustment layer508, the first light-emitting layer 510, the second light-emitting layer512, the electron-transport layer 533(1), the electron-transport layer533(2), the electron-injection layer 534, the upper electrode 514(1),and the upper electrode 514(2) were sequentially formed. The fabricationmethod is described in detail below.

First, the pressure in the vacuum evaporation apparatus was reduced to10⁻⁴ Pa. Then, on the transparent conductive layer 506, thehole-injection layer 531 was formed by co-evaporation of PCPPn andmolybdenum oxide at a weight ratio of 2:1 (PcPPn:molybdenum oxide). Notethat the thickness of the hole-injection layer 531 was 55 nm in thelight-emitting element 13, and the thickness of the hole-injection layer531 was 40 nm in the light-emitting element 14.

Then, the hole-transport layer 532 was formed on the hole-injectionlayer 531. As the hole-transport layer 532, PCPPn was evaporated. Notethat the thickness of the hole-transport layer 532 was 15 nm.

Then, the optical adjustment layer 508 was formed on the hole-transportlayer 532. As the optical adjustment layer 508, BPAFLP was evaporated toa thickness of 20 nm.

Then, the first light-emitting layer 510 was formed on the opticaladjustment layer 508. The first light-emitting layer 510 was formed byco-evaporation of 2mDBTBPDBq-II, PCBBiF, and Ir(tBuppm)₂(acac) at aweight ratio of 0.8:0.2:0.06 (2mDBTBPDBq-II:PCBBiF: Ir(tBuppm)₂(acac)).Note that the thickness of the first light-emitting layer 510 was 25 nm.

Then, the second light-emitting layer 512 was formed on the firstlight-emitting layer 510. The second light-emitting layer 512 was formedby co-evaporation of cgDBCzPA and 1,6BnfAPm-03 at a weight ratio of1:0.05 (cgDBCzPA: 1,6BnfAPrn-03). Note that the thickness of the secondlight-emitting layer 512 was 25 nm.

Then, on the second light-emitting layer 512, the electron-transportlayer 533(1) was formed by evaporation of cgDBCzPA to a thickness of 5nm. Then, on the electron-transport layer 533(1), the electron-transportlayer 533(2) was formed by evaporation of NBphen to a thickness of 15nm. Then, on the electron-transport layer 533(2), the electron-injectionlayer 534 was formed by evaporation of LiF to a thickness of 1 nm.

Then, on the electron-injection layer 534, the upper electrode 514(1)was formed by co-evaporation of Ag and Mg at a volume ratio of 1:0.1.Note that the thickness of the upper electrode 514(1) was 15 nm. Then,on the upper electrode 514(1), ITO was deposited as the upper electrode514(2) by a sputtering method to a thickness of 70 nm.

Note that as illustrated in FIG. 56C and shown in Table 9, the sealingsubstrates 550 of the light-emitting elements 13 and 14 are eachprovided with the coloring layer 556. In Reference Example 2, a red (R)color filter was formed as the coloring layer 556 of the light-emittingelement 13, and a green (G) color filter was formed as the coloringlayer 556 of the light-emitting element 14.

Each of the light-emitting elements over the substrate 502 fabricated asdescribed above was sealed by being bonded to the sealing substrate 550in a glove box in a nitrogen atmosphere so as not to be exposed to theair. Note that the sealing method was the same as that in Example 1.

Through the above process, the light-emitting elements 13 and 14 werefabricated.

<5-2. Fabrication of Light-Emitting Element 15>

First, over the substrate 502, APC was formed as the lower electrode 504by a sputtering method. Note that the thickness of the lower electrode504 was 100 nm and the area of the lower electrode 504 was 4 mm² (2 mm×2mm).

Then, over the lower electrode 504, ITSO was deposited as thetransparent conductive layer 506 by a sputtering method. Note that thethickness of the transparent conductive layer 506 was 10 nm.

Then, as pretreatment of evaporation of an organic compound layer, thetransparent conductive layer 506 side of the substrate 502 provided withthe lower electrode 504 and the transparent conductive layer 506 waswashed with water, baking was performed at 200° C. for one hour, andthen UV ozone treatment was performed on a surface of the transparentconductive layer 506 for 370 seconds.

After that, the substrate 502 was transferred into a vacuum evaporationapparatus where the pressure had been reduced to approximately 10⁻⁴ Pa,and was subjected to vacuum baking at 170° C. for 60 minutes in aheating chamber of the vacuum evaporation apparatus, and then thesubstrate 502 was cooled down for about 30 minutes.

Then, the substrate 502 was fixed to a holder provided in the vacuumevaporation apparatus so that a surface of the substrate 502 over whichthe transparent conductive layer 506 was formed faced downward. InReference Example 2, by a vacuum evaporation method, the hole-injectionlayer 531, the hole-transport layer 532, the second light-emitting layer512, the electron-transport layer 533(1), the electron-transport layer533(2), the electron-injection layer 534, the upper electrode 514(1),and the upper electrode 514(2) were sequentially formed. That is, theoptical adjustment layer 508 and the first light-emitting layer 510 arenot formed, unlike in the light-emitting elements 13 and 14. Thefabrication method is described in detail below.

First, the pressure in the vacuum evaporation apparatus was reduced to10⁻⁴ Pa. Then, on the transparent conductive layer 506, thehole-injection layer 531 was formed by co-evaporation of PCPPn andmolybdenum oxide at a weight ratio of 2:1 (PcPPn:molybdenum oxide). Notethat the thickness of the hole-injection layer 531 was 102.5 nm.

Then, the hole-transport layer 532 was formed on the hole-injectionlayer 531. As the hole-transport layer 532, PCPPn was evaporated. Notethat the thickness of the hole-transport layer 532 was 15 nm.

Then, the second light-emitting layer 512 was formed on thehole-transport layer 532. The second light-emitting layer 512 was formedby co-evaporation of cgDBCzPA and 1,6BnfAPrn-03 at a weight ratio of1:0.05 (cgDBCzPA: 1,6BnfAPm-03). Note that the thickness of the secondlight-emitting layer 512 was 25 nm.

Then, on the second light-emitting layer 512, the electron-transportlayer 533(1) was formed by evaporation of cgDBCzPA to a thickness of 5nm. Then, on the electron-transport layer 533(1), the electron-transportlayer 533(2) was formed by evaporation of NBphen to a thickness of 15nm. Then, on the electron-transport layer 533(2), the electron-injectionlayer 534 was formed by evaporation of LiF to a thickness of 1 nm.

Then, on the electron-injection layer 534, the upper electrode 514(1)was formed by co-evaporation of Ag and Mg at a volume ratio of 1:0.1.Note that the thickness of the upper electrode 514(1) was 15 nm. Then,on the upper electrode 514(1), ITO was deposited as the upper electrode514(2) by a sputtering method to a thickness of 70 nm.

Note that as illustrated in FIG. 56D and shown in Table 9, the sealingsubstrate 550 of the light-emitting element 15 is provided with thecoloring layer 556. In Reference Example 2, a blue (B) color filter wasformed as the coloring layer 556 of the light-emitting element 15.

The light-emitting element over the substrate 502 fabricated asdescribed above was sealed by being bonded to the sealing substrate 550in a glove box in a nitrogen atmosphere so as not to be exposed to theair. Note that the sealing method was the same as that in Example 1.

Through the above process, the light-emitting element 15 was fabricated.

Note that in all the above evaporation steps for the light-emittingelements 13 to 15, a resistive heating method was used as an evaporationmethod.

<5-3. Characteristics of Light-Emitting Elements 13 to 15>

FIGS. 59A, 59B, and 60A show luminance-current density characteristics,luminance-voltage characteristics, and current efficiency-luminancecharacteristics, respectively, of the light-emitting elements 13 to 15.Note that the measurements of the light-emitting elements were carriedout at room temperature (in an atmosphere kept at 25° C.).

Table 10 shows element characteristics of the light-emitting elements 13to 15 at around 1000 cd/m².

TABLE 10 Voltage Current Current density Chromaticity Luminance Currentefficiency (V) (mA) (mA/cm²) (x, y) (cd/m²) (cd/A) Light-emitting 4.00.30 7.6 (0.67, 0.33) 903 11.9 element 13 Light-emitting 3.6 0.06 1.4(0.28, 0.71) 965 68.0 element 14 Light-emitting 3.4 1.20 30.0 (0.14,0.05) 957 3.2 element 15

FIG. 60B shows emission spectra when a current at a current density of2.5 mA/cm² was supplied to the light-emitting elements 13 to 15. Asshown in FIG. 60B, an emission spectrum of the light-emitting element 13has a peak in the red wavelength range, an emission spectrum of thelight-emitting element 14 has a peak in the green wavelength range, andan emission spectrum of the light-emitting element 15 has a peak in theblue wavelength range.

As shown in Table 10, FIGS. 59A and 59B, and FIGS. 60A and 60B, thelight-emitting elements 13 to 15 each have element characteristicshaving high efficiency and light emission in a desired wavelength range.Since the light-emitting elements 14 and 15 are each provided with thecoloring layer 556, they have higher color purity than thelight-emitting elements 11 and 12 in Reference Example 1.

Reference Example 3

Light-emitting elements (a light-emitting element 16, a light-emittingelement 17, and a light-emitting element 18) in modes different fromthose of the light-emitting elements described in Examples 1 to 3 andReference Examples 1 and 2 were fabricated and evaluated below.

Schematic cross-sectional views of the light-emitting elements 16 and 17are each illustrated in FIG. 56C, a schematic cross-sectional view ofthe light-emitting element 18 is illustrated in FIG. 56D, and thedetailed structures of the elements of the light-emitting elements 16 to18 are shown in Table 11. Note that the compounds used here are the sameas those used in Reference Example 1.

TABLE 11 Layer Reference numeral Thickness (nm) Material Weight ratioLight- Coloring layer 556 — Red*¹⁾ — emitting Upper electrode 514(2) 70ITO — element 16 514(1) 15 Ag:Mg 1:0.1*²⁾ Electron-injection 534 1 LiF —layer Electron- 533(2) 15 NBphen — transport layer 533(1) 5 cgDBCzPA —Second light- 512 25 cgDBCzPA:1,6BnfAPrn-03 1:0.02 emitting layer Firstlight-emitting 510(2) 15 2mDBTBPDBq-II:Ir(tBuppm)₂(acac) 1:0.06 layer510(1) 20 2mDBTBPDBq-II:PCBBiF:Ir(tBuppm)₂(acac) 0.8:0.2:0.06 Optical508 25 PCBBiF — adjustment layer Hole-transport 532 15 PCPPn — layerHole-injection 531 40 PCPPn:MoO_(x) 2:1 layer Transparent 506 110 ITSO —conductive layer Lower electrode 504 100 APC — Light- Coloring layer 556— Green*¹⁾ — emitting Upper electrode 514(2) 70 ITO — element 17 514(1)15 Ag:Mg 1:0.1*²⁾ Electron-injection 534 1 LiF — layer Electron- 533(2)15 NBphen — transport layer 533(1) 5 cgDBCzPA — Second light- 512 25cgDBCzPA:1,6BnfAPrn-03 1:0.02 emitting layer First light-emitting 510(2)15 2mDBTBPDBq-II:Ir(tBuppm)₂(acac) 1:0.06 layer 510(1) 202mDBTBPDBq-II:PCBBiF:Ir(tBuppm)₂(acac) 0.8:0.2:0.06 Optical 508 25PCBBiF — adjustment layer Hole-transport 532 15 PCPPn — layerHole-injection 531 32.5 PCPPn:MoO_(x) 2:1 layer Transparent 506 85 ITSO— conductive layer Lower electrode 504 100 APC — Light- Coloring layer556 — Blue*¹⁾ — emitting Upper electrode 514(2) 70 ITO — element 18514(1) 15 Ag:Mg 1:0.1*²⁾ Electron-injection 534 1 LiF — layer Electron-533(2) 15 NBphen — transport layer 533(1) 5 cgDBCzPA — Second light- 51225 cgDBCzPA:1,6BnfAPrn-03 1:0.02 emitting layer First light-emitting — —— — layer — — — — Optical — — — — adjustment layer Hole-transport 532 15PCPPn — layer Hole-injection 531 30 PCPPn:MoO_(x) 2:1 layer Transparent506 85 ITSO — conductive layer Lower electrode 504 100 APC — *¹⁾color*²⁾volume ratio<6-1. Fabrication of Light-Emitting Elements 16 and 17>

First, over the substrate 502, APC was formed as the lower electrode 504by a sputtering method. Note that the thickness of the lower electrode504 was 100 nm and the area of the lower electrode 504 was 4 mm² (2 mm×2mm).

Then, over the lower electrode 504, a film of ITSO was formed as thetransparent conductive layer 506 by a sputtering method. Note that thethickness of the transparent conductive layer 506 was 110 nm in thelight-emitting element 16, and the thickness of the transparentconductive layer 506 was 85 nm in the light-emitting element 17.

Then, as pretreatment of evaporation of an organic compound layer, thetransparent conductive layer 506 side of the substrate 502 provided withthe lower electrode 504 and the transparent conductive layer 506 waswashed with water, baking was performed at 200° C. for one hour, andthen UV ozone treatment was performed on a surface of the transparentconductive layer 506 for 370 seconds.

After that, the substrate 502 was transferred into a vacuum evaporationapparatus where the pressure had been reduced to approximately 10⁻⁴ Pa,and was subjected to vacuum baking at 170° C. for 60 minutes in aheating chamber of the vacuum evaporation apparatus, and then thesubstrate 502 was cooled down for about 30 minutes.

Then, the substrate 502 was fixed to a holder provided in the vacuumevaporation apparatus so that a surface of the substrate 502 over whichthe transparent conductive layer 506 was formed faced downward. InReference Example 3, by a vacuum evaporation method, the hole-injectionlayer 531, the hole-transport layer 532, the optical adjustment layer508, the first light-emitting layer 510, the second light-emitting layer512, the electron-transport layer 533(1), the electron-transport layer533(2), the electron-injection layer 534, the upper electrode 514(1),and the upper electrode 514(2) were sequentially formed. The fabricationmethod is described in detail below.

First, the pressure in the vacuum evaporation apparatus was reduced to10⁻⁴ Pa. Then, on the transparent conductive layer 506, thehole-injection layer 531 was formed by co-evaporation of PCPPn andmolybdenum oxide at a weight ratio of 2:1 (PcPPn:molybdenum oxide). Notethat the thickness of the hole-injection layer 531 was 40 nm in thelight-emitting element 16, and the thickness of the hole-injection layer531 was 32.5 nm in the light-emitting element 17.

Then, the hole-transport layer 532 was formed on the hole-injectionlayer 531. As the hole-transport layer 532, PCPPn was evaporated. Notethat the thickness of the hole-transport layer 532 was 15 nm.

Then, the optical adjustment layer 508 was formed on the hole-transportlayer 532. As the optical adjustment layer 508, PCBBiF was evaporated toa thickness of 25 nm.

Then, the first light-emitting layer 510(1) was formed on the opticaladjustment layer 508. The first light-emitting layer 510(1) was formedby co-evaporation of 2mDBTBPDBq-II, PCBBiF, and Ir(tBuppm)₂(acac) at aweight ratio of 0.8:0.2:0.06 (2mDBTBPDBq-II:PCBBiF: Ir(tBuppm)₂(acac)).Note that the thickness of the first light-emitting layer 510(1) was 20nm.

Then, the first light-emitting layer 510(2) was formed on the firstlight-emitting layer 510(1). Then, the first light-emitting layer 510(2)was formed by co-evaporation of 2mDBTBPDBq-II and Ir(tBuppm)₂(acac) at aweight ratio of 1:0.06 (2mDBTBPDBq-II: Ir(tBuppm)₂(acac)). Note that thethickness of the first light-emitting layer 510(2) was 15 nm.

Then, the second light-emitting layer 512 was formed on the firstlight-emitting layer 510(2). The second light-emitting layer 512 wasformed by co-evaporation of cgDBCzPA and 1,6BnfAPrn-03 at a weight ratioof 1:0.02 (cgDBCzPA: 1,6BnfAPrn-03). Note that the thickness of thesecond light-emitting layer 512 was 25 nm.

Then, on the second light-emitting layer 512, the electron-transportlayer 533(1) was formed by evaporation of cgDBCzPA to a thickness of 5nm. Then, on the electron-transport layer 533(1), the electron-transportlayer 533(2) was formed by evaporation of NBphen to a thickness of 15nm. Then, on the electron-transport layer 533(2), the electron-injectionlayer 534 was formed by evaporation of LiF to a thickness of 1 nm.

Then, on the electron-injection layer 534, the upper electrode 514(1)was formed by co-evaporation of Ag and Mg at a volume ratio of 1:0.1.Note that the thickness of the upper electrode 514(1) was 15 nm. Then,on the upper electrode 514(1), ITO was deposited as the upper electrode514(2) by a sputtering method to a thickness of 70 nm.

Note that as illustrated in FIG. 56C and shown in Table 11, the sealingsubstrate 550 of the light-emitting elements 16 and 17 are each providedwith the coloring layer 556. In Reference Example 3, a red (R) colorfilter was formed as the coloring layer 556 of the light-emittingelement 16, and a green (G) color filter was formed as the coloringlayer 556 of the light-emitting element 17.

Each of the light-emitting elements over the substrate 502 fabricated asdescribed above was sealed by being bonded to the sealing substrate 550in a glove box in a nitrogen atmosphere so as not to be exposed to theair. Note that the sealing method was the same as that in Example 1.

Through the above process, the light-emitting elements 16 and 17 werefabricated.

<6-2. Fabrication of Light-Emitting Element 18>

First, over the substrate 502, APC was formed as the lower electrode 504by a sputtering method. Note that the thickness of the lower electrode504 was 100 nm and the area of the lower electrode 504 was 4 mm² (2 mm×2mm).

Then, over the lower electrode 504, ITSO was deposited as thetransparent conductive layer 506 by a sputtering method. Note that thethickness of the transparent conductive layer 506 was 85 nm.

Then, as pretreatment of evaporation of an organic compound layer, thetransparent conductive layer 506 side of the substrate 502 provided withthe lower electrode 504 and the transparent conductive layer 506 waswashed with water, baking was performed at 200° C. for one hour, andthen UV ozone treatment was performed on a surface of the transparentconductive layer 506 for 370 seconds.

After that, the substrate 502 was transferred into a vacuum evaporationapparatus where the pressure had been reduced to approximately 10⁻⁴ Pa,and was subjected to vacuum baking at 170° C. for 60 minutes in aheating chamber of the vacuum evaporation apparatus, and then thesubstrate 502 was cooled down for about 30 minutes.

Then, the substrate 502 was fixed to a holder provided in the vacuumevaporation apparatus so that a surface of the substrate 502 over whichthe transparent conductive layer 506 was formed faced downward. InReference Example 3, by a vacuum evaporation method, the hole-injectionlayer 531, the hole-transport layer 532, the second light-emitting layer512, the electron-transport layer 533(1), the electron-transport layer533(2), the electron-injection layer 534, the upper electrode 514(1),and the upper electrode 514(2) were sequentially formed. That is, theoptical adjustment layer 508 and the first light-emitting layer 510 arenot formed, unlike the light-emitting elements 16 and 17. Thefabrication method is described in detail below.

First, the pressure in the vacuum evaporation apparatus was reduced to10⁻⁴ Pa. Then, on the transparent conductive layer 506, thehole-injection layer 531 was formed by co-evaporation of PCPPn andmolybdenum oxide at a weight ratio of 2:1 (PcPPn:molybdenum oxide). Notethat the thickness of the hole-injection layer 531 was 30 nm.

Then, the hole-transport layer 532 was formed on the hole-injectionlayer 531. As the hole-transport layer 532, PCPPn was evaporated. Notethat the thickness of the hole-transport layer 532 was 15 nm.

Then, the second light-emitting layer 512 was formed on thehole-transport layer 532. The second light-emitting layer 512 was formedby co-evaporation of cgDBCzPA and 1,6BnfAPm-03 at a weight ratio of1:0.02 (cgDBCzPA: 1,6BnfAPm-03). Note that the thickness of the secondlight-emitting layer 512 was 25 nm.

Then, on the second light-emitting layer 512, the electron-transportlayer 533(1) was formed by evaporation of cgDBCzPA to a thickness of 5nm. Then, on the electron-transport layer 533(1), the electron-transportlayer 533(2) was formed by evaporation of NBphen to a thickness of 15nm. Then, on the electron-transport layer 533(2), the electron-injectionlayer 534 was formed by evaporation of LiF to a thickness of 1 nm.

Then, on the electron-injection layer 534, the upper electrode 514(1)was formed by co-evaporation of Ag and Mg at a volume ratio of 1:0.1.Note that the thickness of the upper electrode 514(1) was 15 nm. Then,on the upper electrode 514(1), ITO was deposited as the upper electrode514(2) by a sputtering method to a thickness of 70 nm.

Note that as illustrated in FIG. 56D and shown in Table 11, the sealingsubstrate 550 of the light-emitting element 18 is provided with thecoloring layer 556. In Reference Example 3, a blue (B) color filter wasformed as the coloring layer 556 of the light-emitting element 18.

The light-emitting element over the substrate 502 fabricated asdescribed above was sealed by being bonded to the sealing substrate 550in a glove box in a nitrogen atmosphere so as not to be exposed to theair. Note that the sealing method was the same as that in Example 1.

Through the above process, the light-emitting element 18 was fabricated.

Note that in all the above evaporation steps for the light-emittingelements 16 to 18, a resistive heating method was used as an evaporationmethod.

<6-3. Characteristics of Light-Emitting Elements 16 to 18>

FIGS. 61A, 61B, and 62A show luminance-current density characteristics,luminance-voltage characteristics, and current efficiency-luminancecharacteristics, respectively, of the light-emitting elements 16 to 18.Note that the measurements of the light-emitting elements were carriedout at room temperature (in an atmosphere kept at 25° C.).

Table 12 shows element characteristics of the light-emitting elements 16to 18 at around 1000 cd/m².

TABLE 12 Voltage Current Current density Chromaticity Luminance Currentefficiency (V) (mA) (mA/cm²) (x, y) (cd/m²) (cd/A) Light-emitting 4.00.29 7.4 (0.66, 0.34) 1056 14.4 element 16 Light-emitting 3.3 0.03 0.8(0.30, 0.69) 1005 122.0 element 17 Light-emitting 3.3 1.19 29.7 (0.14,0.05) 953 3.2 element 18

FIG. 62B shows emission spectra when a current at a current density of2.5 mA/cm² was supplied to the light-emitting elements 16 to 18. Asshown in FIG. 62B, an emission spectrum of the light-emitting element 16has a peak in the red wavelength range, an emission spectrum of thelight-emitting element 17 has a peak in the green wavelength range, andan emission spectrum of the light-emitting element 18 has a peak in theblue wavelength range.

As shown in Table 12, FIGS. 61A and 61B, and FIGS. 62A and 62B, thelight-emitting elements 16 to 18 each have element characteristicshaving high efficiency and light emission in a desired wavelength range.

Next, a reliability test was performed on each of the light-emittingelements 16 to 18. FIG. 63 shows results of the reliability tests.

In the reliability test, each of the light-emitting elements 16 to 18was driven under the conditions where the initial luminance was 5000cd/m² and the current density was constant. In FIG. 63, the verticalaxis represents normalized luminance (%) with the initial luminance of100%, and the horizontal axis represents driving time (h) of theelement. The results in FIG. 63 indicate that the normalized luminanceof the light-emitting element 16 after 831 hours was 88%, the normalizedluminance of the light-emitting element 17 after 2013 hours was 91%, andthe normalized luminance of the light-emitting element 18 after 1850hours was 85%.

The results in FIGS. 61A and 61B, FIGS. 62A and 62B, and FIG. 63indicate that the light-emitting elements 16 to 18, each of which isReference Example 3, have excellent element characteristics(voltage-luminance characteristics, luminance-current efficiencycharacteristics, and voltage-current characteristics) and highreliability (normalized luminance-time characteristics). However, thelight-emitting elements 16 to 18 leave room for improvement inreliability as compared with the light-emitting elements 7 to 9 of oneembodiment of the present invention in Example 3.

Reference Example 4

A method for synthesizing 1,6BnfAPm-03 that is the organic compound usedin any of the above examples and reference examples is described below.Note that the structure of 1,6BnfAPm-03 is shown below.

Step 1: Synthesis of 6-iodobenzo[b]naphtho[1,2-d]furan

Into a 500 mL three-neck flask were put 8.5 g (39 mmol) ofbenzo[b]naphtho[1,2-d]furan, and the air in the flask was replaced withnitrogen. Then, 195 mL of tetrahydrofuran was added thereto. Thissolution was cooled to −75° C. Then, 25 mL (40 mmol) of n-butyllithium(a 1.59 mol/L n-hexane solution) was dropped into this solution. Afterthe drop, the resulting solution was stirred at room temperature for onehour.

After a predetermined period of time, the resulting solution was cooledto −75° C. Then, a solution in which 10 g (40 mmol) of iodine had beendissolved in 40 mL of THF was dropped into this solution. After thedrop, the resulting solution was stirred for 17 hours while thetemperature of the solution was returned to room temperature. After apredetermined period of time, an aqueous solution of sodium thiosulfatewas added to the mixture, and the resulting mixture was stirred for onehour. Then, an organic layer of the mixture was washed with water anddried with magnesium sulfate. After the drying, the mixture wasgravity-filtered to give a solution. The resulting solution wassuction-filtered through Celite (Catalog No. 531-16855 produced by WakoPure Chemical Industries, Ltd.) and Florisil (Catalog No. 540-00135produced by Wako Pure Chemical Industries, Ltd.) to give a filtrate. Theresulting filtrate was concentrated to give a solid. The resulting solidwas recrystallized from toluene to give 6.0 g (18 mmol) of a whitepowder of the target substance in 45% yield. A synthesis scheme of Step1 is shown in (a-1).

Step 2: Synthesis of 6-phenylbenzo[b]naphtho[1,2-d]furan

Into a 200 mL three-neck flask were put 6.0 g (18 mmol) of6-iodobenzo[b]naphtho[1,2-d]furan, 2.4 g (19 mmol) of phenylboronicacid, 70 mL of toluene, 20 mL of ethanol, and 22 mL of an aqueoussolution of potassium carbonate (2.0 mol/L). This mixture was degassedby being stirred while the pressure was reduced. After the degassing,the air in the flask was replaced with nitrogen, and then 480 mg (0.42mmol) of tetrakis(triphenylphosphine)palladium(0) was added to themixture. The resulting mixture was stirred at 90° C. under a nitrogenstream for 12 hours.

After a predetermined period of time, water was added to the mixture,and an aqueous layer was subjected to extraction with toluene. Theextracted solution and an organic layer were combined, and the mixturewas washed with water and then dried with magnesium sulfate. The mixturewas gravity-filtered to give a filtrate. The resulting filtrate wasconcentrated to give a solid, and the resulting solid was dissolved intoluene. The resulting solution was suction-filtered through Celite(Catalog No. 531-16855 produced by Wako Pure Chemical Industries, Ltd.),Florisil (Catalog No. 540-00135 produced by Wako Pure ChemicalIndustries, Ltd.), and alumina to give a filtrate. The resultingfiltrate was concentrated to give a solid. The resulting solid wasrecrystallized from toluene to give a 4.9 g (17 mmol) of a white solidof the target substance in 93% yield. A synthesis scheme of Step 2 isshown in (a-2).

Step 3: Synthesis of 8-iodo-6-phenylbenzo[b]naphtho[1,2-d]furan

Into a 300 mL three-neck flask was put 4.9 g (17 mmol) of6-phenylbenzo[b]naphtho[1,2-d]furan, and the air in the flask wasreplaced with nitrogen. Then, 87 mL of tetrahydrofuran (THF) was addedthereto. The resulting solution was cooled to −75° C. Then, 11 mL (18mmol) of n-butyllithium (a 1.59 mol/L n-hexane solution) was droppedinto the solution. After the drop, the resulting solution was stirred atroom temperature for one hour. Then, a solution in which 4.6 g (18 mmol)of iodine had been dissolved in 18 mL of THF was dropped into theresulting solution.

The resulting solution was stirred for 17 hours while the temperature ofthe solution was returned to room temperature. After a predeterminedperiod of time, an aqueous solution of sodium thiosulfate was added tothe mixture, and the resulting mixture was stirred for one hour. Then,an organic layer of the mixture was washed with water and dried withmagnesium sulfate. The mixture was gravity-filtered to give a filtrate.The resulting filtrate was suction-filtered through Celite (Catalog No.531-16855 produced by Wako Pure Chemical Industries, Ltd.), Florisil(Catalog No. 540-00135 produced by Wako Pure Chemical Industries, Ltd.),and alumina to give a filtrate. The resulting filtrate was concentratedto give a solid. The resulting solid was recrystallized from toluene togive 3.7 g (8.8 mmol) of a white solid of the target substance in 53%yield. A synthesis scheme of Step 3 is shown in (a-3).

Step 4: Synthesis of 1,6BnfAPrn-03

Into a 100 mL three-neck flask were put 0.71 g (2.0 mmol) of1,6-dibromopyrene, 1.0 g (10.4 mmol) of sodium-tert-butoxide, 10 mL oftoluene, 0.36 mL (4.0 mmol) of aniline, and 0.3 mL oftri(tert-butyl)phosphine (a 10 wt % hexane solution), and the air in theflask was replaced with nitrogen. To this mixture was added 50 mg (85μmol) of bis(dibenzylideneacetone)palladium(0), and the resultingmixture was stirred at 80° C. for 2 hours.

After a predetermined period of time, to the resulting mixture wereadded 1.7 g (4.0 mmol) of 8-iodo-6-phenylbenzo[b]naphtho[1,2-d]furan,180 mg (0.44 mmol) of 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl(abbreviation: S-Phos), and 50 mg (85 μmol) ofbis(dibenzylideneacetone)palladium(0), and the resulting mixture wasstirred at 100° C. for 15 hours. After a predetermined period of time,the resulting mixture was filtered through Celite (Catalog No. 531-16855produced by Wako Pure Chemical Industries, Ltd.) to give a filtrate. Theresulting filtrate was concentrated to give a solid. The resulting solidwas washed with ethanol and recrystallized from toluene to give 1.38 g(1.4 mmol) of a yellow solid of the target substance in 71% yield.

By a train sublimation method, 1.37 g (1.4 mmol) of the resulting yellowsolid was purified by sublimation. The purification by sublimation wasconducted by heating the yellow solid at 370° C. at an argon flow rateof 10 mL/min under a pressure of under a pressure of 2.3 Pa. As a resultof the purification by sublimation, 0.68 g (0.70 mmol) of the yellowsolid was recovered at a collection rate of 50%. A synthesis scheme ofStep 4 is shown in (a-4).

Analysis results by nuclear magnetic resonance (¹H NMR) spectroscopy ofthe yellow solid obtained in Step 4 are described below.

¹H NMR (dichloromethane-d2, 500 MHz): δ=6.88 (t, J=7.7 Hz, 4H),7.03-7.06 (m, 6H), 7.11 (t, J=7.5 Hz, 2H), 7.13 (d, J=8.0 Hz, 2H),7.28-7.32 (m, 8H), 7.37 (t, J=8.0 Hz, 2H), 7.59 (t, J=7.2 Hz, 2H), 7.75(t, J=7.7 Hz, 2H), 7.84 (d, J=9.0 Hz, 2H), 7.88 (d, J=8.0 Hz, 2H), 8.01(s, 2H), 8.07 (d, J=8.0 Hz, 4H), 8.14 (d, J=9.0 Hz, 2H), 8.21 (d, J=8.0Hz, 2H), 8.69 (d, J=8.5 Hz, 2H).

Reference Example 5

An example of a method for synthesizing Ir(iBu5bpm)₂(acac) that is thenovel compound used in the above example is described below. Thestructure of Ir(iBu5bpm)₂(acac) is shown below.

Step 1: Synthesis of 4-chloro-6-(2-methylpropyl)pyrimidine

First, into a 200 mL three-neck flask were put 1.02 g of4,6-dichloropyrimidine, 0.14 g of tris(2,4-pentanedionato)iron(III)(abbreviation: Fe(acac)₃), 67 mL of dry THF, and 5.6 mL of1-methyl-2-pyrrolidone (abbreviation: NMP), and the air in the flask wasreplaced with nitrogen. The flask was cooled with ice, 6.7 mL of a 1MTHF solution of isobutylmagnesium bromide (abbreviation: iBuMgBr) wasadded, and the mixture was stirred at room temperature for 20 hours.Then, 1 M hydrochloric acid was added, and an organic layer wassubjected to extraction with ethyl acetate. The extracted solution waswashed with a saturated aqueous solution of sodium hydrogen carbonateand a saturated aqueous solution of sodium chloride, and dried overmagnesium sulfate. The solution obtained by the drying was filtrated.The solvent of this solution was distilled off, and then the obtainedresidue was purified by flash column chromatography using a developingsolvent in which the volume ratio of dichloromethane to ethyl acetatewas 10:1 to give yellow oil of the target substance in 65% yield. Asynthetic scheme of Step 1 is shown in (b-1) below.

Step 2: Synthesis of 4-isobutyl-6-(biphenyl-3-yl)pyrimidine(abbreviation: HiBu5bpm)

Next, into a recovery flask equipped with a reflux pipe were put 1.50 gof 4-chloro-6-(2-methylpropyl)pyrimidine obtained in Step 1, 2.57 g of3-biphenylboronic acid, 4.06 g of sodium carbonate, 0.077 g ofbis(triphenylphosphine)palladium(II) dichloride (abbreviation:PdCl₂(PPh₃)₂), 20 mL of water, and 20 mL of DMF, and the air in theflask was replaced with argon. This reaction container was heated byirradiation with microwaves (2.45 GHz, 100 W) for 2 hours. Note that theirradiation with microwaves was performed using a microwave synthesissystem (Discover, manufactured by CEM Corporation). Then, water wasadded to this solution and an organic layer was subjected to extractionwith dichloromethane. The obtained organic layer was washed with waterand saturated saline, and was dried with magnesium sulfate. The solutionobtained by the drying was filtrated. The solvent of this solution wasdistilled off, and then the obtained residue was purified by flashcolumn chromatography using a developing solvent in which the volumeratio of hexane to ethyl acetate was 2:1 to give pale yellow oil of thetarget pyrimidine derivative HiBu5bpm (abbreviation) in 95% yield. Asynthetic scheme of Step 2 is shown in (b-2) below.

Step 3: Synthesis ofdi-μ-chloro-tetrakis{4-phenyl-2-[6-(2-methylpropyl)-4-pyrimidinyl-κN3]phenyl-κC}diiridium(III) (abbreviation: [Ir(iBu5bpm)₂Cl]₂)

Next, into a recovery flask equipped with a reflux pipe were put 30 mLof 2-ethoxyethanol, 10 mL of water, 2.38 g of HiBu5bpm (abbreviation)obtained in Step 2, and 1.17 g of iridium chloride hydrate (IrCl₃.nH₂O)(manufactured by Furuya Metal Co., Ltd.), and the air in the flask wasreplaced with argon. After that, irradiation with microwaves (2.45 GHz,100 W) was performed for one hour to cause a reaction. The solvent wasdistilled off, and then the obtained residue was suction-filtered andwashed with methanol to give a green powder of [Ir(iBu5bpm)₂Cl]₂(abbreviation) that is a dinuclear complex in 34% yield. A syntheticscheme of Step 3 is shown in (b-3) below.

Step 4: Synthesis of bis{4-phenyl-2-[6-(2-methylpropyl)-4-pyrimidinyl-κN3]phenyl-κC}(2,4-pentanedionato-κ²O,O′)iridium(III) (abbreviation: Ir(iBu5bpm)₂(acac))

Furthermore, into a recovery flask equipped with a reflux pipe were put20 mL of 2-ethoxyethanol, 1.10 g of [Ir(iBu5bpm)₂Cl]₂ (abbreviation)that is the Binuclear complex obtained in Step 3, 0.21 g ofacetylacetone (abbreviation: Hacac), and 0.73 g of sodium carbonate, andthe air in the flask was replaced with argon. After that, the mixturewas heated by irradiation with microwaves (2.45 GHz, 120 W) for 60minutes. Furthermore, 0.21 g of Hacac (abbreviation) was added, and thereaction container was heated by being irradiated with microwaves (2.45GHz, 120 W) for 60 minutes. The solvent was distilled off, and then theobtained residue was suction-filtered with methanol and washed withwater and methanol. After the obtained solid was purified by flashcolumn chromatography using a developing solvent in which the volumeratio of dichloromethane to ethyl acetate was 10:1, recrystallizationwas performed with a mixed solvent of dichloromethane and methanol togive a yellow orange powder of Ir(iBu5bpm)₂(acac) that is a novelcompound in 27% yield. By a train sublimation method, 0.32 g of theobtained yellow orange powder solid was purified. In the purification bysublimation, the solid was heated at 285° C. under a pressure of 2.7 Pawith an argon flow rate of 5 mL/min. After the sublimation purification,a yellow orange solid of the target substance in 88% yield was obtained.A synthetic scheme of Step 4 is shown in (b-4) below.

Analysis results by nuclear magnetic resonance (¹H NMR) spectroscopy ofthe yellow powder obtained in Step 4 are described below. FIG. 64 showsthe ¹H NMR chart.

¹H NMR. δ (CD₂Cl₂): 1.06 (t, 12H), 1.83 (s, 6H), 2.27-2.32 (m, 2H), 2.89(d, 4H), 5.36 (s, 1H), 6.49 (d, 2H), 7.08 (d, 2H), 7.30 (t, 2H), 7.40(t, 4H), 7.55 (d, 4H), 7.74 (s, 2H), 7.91 (s, 2H), 9.03 (s, 2H).

Next, an ultraviolet-visible absorption spectrum (hereinafter simplyreferred to as an “absorption spectrum”) and an emission spectrum of adichloromethane solution of Ir(iBu5bpm)₂(acac) were measured. Themeasurement of the absorption spectrum was conducted at roomtemperature, for which an ultraviolet-visible light spectrophotometer(V550 type manufactured by JASCO Corporation) was used and thedichloromethane solution (9.6 μmol/L) was put in a quartz cell. Inaddition, the measurement of the emission spectrum was conducted at roomtemperature, for which an absolute PL quantum yield measurement system(C11347-01 manufactured by Hamamatsu Photonics K. K.) was used. Thedeoxidized dichloromethane solution (9.6 μmol/L) was sealed in a quartzcell under a nitrogen atmosphere in a glove box (LABstar M13 (1250/780))manufactured by Bright Co., Ltd. Measurement results of the obtainedabsorption and emission spectra are shown in FIG. 65, in which thehorizontal axis represents wavelength and the vertical axes representabsorption intensity and emission intensity. In FIG. 65 where there aretwo solid lines, the thin line represents the absorption spectrum andthe thick line represents the emission spectrum. Note that theabsorption spectrum in FIG. 65 is the results obtained in such a waythat the absorption spectrum measured by putting only dichloromethane ina quartz cell was subtracted from the absorption spectrum measured byputting the dichloromethane solution (9.6 μmol/L) in a quartz cell.

As shown in FIG. 65, Ir(iBu5bpm)₂(acac) has an emission peak at 555 nm,and yellow light emission was observed from the dichloromethanesolution.

Furthermore, weight loss percentage of Ir(iBu5bpm)₂(acac) was measuredby a high vacuum differential type differential thermal balance (TG/DTA2410SA, manufactured by Bruker AXS K.K.). The temperature was increasedat a rate of 10° C./min under a degree of vacuum of 10 Pa. As a result,the weight loss percentage of Ir(iBu5bpm)₂(acac) was found to be 100% ata temperature lower than 300° C. as shown in FIG. 66, which indicated afavorable sublimation property.

This application is based on Japanese Patent Application serial no.2014-200297 filed with Japan Patent Office on Sep. 30, 2014 and JapanesePatent Application serial no. 2014-200298 filed with Japan Patent Officeon Sep. 30, 2014, the entire contents of which are hereby incorporatedby reference.

What is claimed is:
 1. A light-emitting device comprising: a firstlight-emitting element comprising: a first lower electrode; a firsttransparent conductive layer over the first lower electrode; an opticaladjustment layer over the first transparent conductive layer; a firstlight-emitting layer over the optical adjustment layer; a secondlight-emitting layer over the first light-emitting layer; and an upperelectrode over the second light-emitting layer; a second light-emittingelement comprising: a second lower electrode; a second transparentconductive layer over the second lower electrode; the optical adjustmentlayer over the second transparent conductive layer; the firstlight-emitting layer over the optical adjustment layer; the secondlight-emitting layer over the first light-emitting layer; and the upperelectrode over the second light-emitting layer; and a thirdlight-emitting element comprising: a third lower electrode; a thirdtransparent conductive layer over the third lower electrode; the secondlight-emitting layer over the third transparent conductive layer; andthe upper electrode over the second light-emitting layer, wherein athickness of the first transparent conductive layer is greater than athickness of the second transparent conductive layer, and wherein thethickness of the second transparent conductive layer is substantiallythe same as a thickness of the third transparent conductive layer. 2.The light-emitting device according to claim 1, wherein the firstlight-emitting element further comprises a hole-injection layer over thefirst transparent conductive layer, a hole-transport layer over thehole-injection layer, an electron-transport layer over the secondlight-emitting layer, and an electron-injection layer over theelectron-transport layer, wherein the second light-emitting elementfurther comprises the hole-injection layer over the second transparentconductive layer, the hole-transport layer over the hole-injectionlayer, the electron-transport layer over the second light-emittinglayer, and the electron-injection layer over the electron-transportlayer, and wherein the third light-emitting element further comprisesthe hole-injection layer over the third transparent conductive layer,the hole-transport layer over the hole-injection layer, theelectron-transport layer over the second light-emitting layer, and theelectron-injection layer over the electron-transport layer.
 3. Thelight-emitting device according to claim 1, wherein the firstlight-emitting element further comprises an electron-injection layerover the first transparent conductive layer, an electron-transport layerover the electron-injection layer, a hole-transport layer over thesecond light-emitting layer, and a hole-injection layer over thehole-transport layer, wherein the second light-emitting element furthercomprises the electron-injection layer over the second transparentconductive layer, the electron-transport layer over theelectron-injection layer, the hole-transport layer over the secondlight-emitting layer, and the hole-injection layer over thehole-transport layer, and wherein the third light-emitting elementfurther comprises the electron-injection layer over the thirdtransparent conductive layer, the electron-transport layer over theelectron-injection layer, the hole-transport layer over the secondlight-emitting layer, and the hole-injection layer over thehole-transport layer.
 4. The light-emitting device according to claim 1,wherein an emission spectrum of the first light-emitting elementincludes a peak in a wavelength range of longer than or equal to 600 nmand shorter than or equal to 740 nm, wherein an emission spectrum of thesecond light-emitting element includes a peak in a wavelength range oflonger than or equal to 480 nm and shorter than 600 nm, and wherein anemission spectrum of the third light-emitting element includes a peak ina wavelength range of longer than or equal to 400 nm and shorter than480 nm.
 5. The light-emitting device according to claim 1, wherein adistance between the first lower electrode and the first light-emittinglayer is larger than a distance between the second lower electrode andthe first light-emitting layer, and wherein a distance between thesecond lower electrode and the second light-emitting layer is largerthan a distance between the third lower electrode and the secondlight-emitting layer.
 6. The light-emitting device according to claim 1,wherein an optical path length between the first lower electrode and thefirst light-emitting layer is 3λ_(R)/4 when λ_(R) is a wavelength of redlight, wherein an optical path length between the second lower electrodeand the first light-emitting layer is 3λ_(G)/4 when λ_(G) is awavelength of green light, and wherein an optical path length betweenthe third lower electrode and the second light-emitting layer is3λ_(B)/4 when λ_(B) is a wavelength of blue light.
 7. The light-emittingdevice according to claim 1, wherein the optical adjustment layer has ahole-transport property.
 8. The light-emitting device according to claim1, wherein the first light-emitting layer includes a phosphorescentmaterial, and wherein the second light-emitting layer includes afluorescent material.
 9. A light-emitting device comprising: a firstlight-emitting element comprising: a first lower electrode; a firsttransparent conductive layer over the first lower electrode; an opticaladjustment layer over the first transparent conductive layer; a firstlight-emitting layer over the optical adjustment layer; and a secondlight-emitting layer over the first light-emitting layer; a secondlight-emitting element comprising: a second lower electrode; a secondtransparent conductive layer over the second lower electrode; theoptical adjustment layer over the second transparent conductive layer;the first light-emitting layer over the optical adjustment layer; andthe second light-emitting layer over the first light-emitting layer; athird light-emitting element comprising: a third lower electrode; athird transparent conductive layer over the third lower electrode; andthe second light-emitting layer over the third transparent conductivelayer, wherein a thickness of the first transparent conductive layer isgreater than a thickness of the second transparent conductive layer, andwherein the thickness of the second transparent conductive layer issubstantially the same as a thickness of the third transparentconductive layer.
 10. The light-emitting device according to claim 9,wherein the first light-emitting element further comprises ahole-injection layer over the first transparent conductive layer, ahole-transport layer over the hole-injection layer, anelectron-transport layer over the second light-emitting layer, and anelectron-injection layer over the electron-transport layer, wherein thesecond light-emitting element further comprises the hole-injection layerover the second transparent conductive layer, the hole-transport layerover the hole-injection layer, the electron-transport layer over thesecond light-emitting layer, and the electron-injection layer over theelectron-transport layer, and wherein the third light-emitting elementfurther comprises the hole-injection layer over the third transparentconductive layer, the hole-transport layer over the hole-injectionlayer, the electron-transport layer over the second light-emittinglayer, and the electron-injection layer over the electron-transportlayer.
 11. The light-emitting device according to claim 9, wherein thefirst light-emitting element further comprises an electron-injectionlayer over the first transparent conductive layer, an electron-transportlayer over the electron-injection layer, a hole-transport layer over thesecond light-emitting layer, and a hole-injection layer over thehole-transport layer, wherein the second light-emitting element furthercomprises the electron-injection layer over the second transparentconductive layer, the electron-transport layer over theelectron-injection layer, the hole-transport layer over the secondlight-emitting layer, and the hole-injection layer over thehole-transport layer, and wherein the third light-emitting elementfurther comprises the electron-injection layer over the thirdtransparent conductive layer, the electron-transport layer over theelectron-injection layer, the hole-transport layer over the secondlight-emitting layer, and the hole-injection layer over thehole-transport layer.
 12. The light-emitting device according to claim9, wherein an emission spectrum of the first light-emitting elementincludes a peak in a wavelength range of longer than or equal to 600 nmand shorter than or equal to 740 nm, wherein an emission spectrum of thesecond light-emitting element includes a peak in a wavelength range oflonger than or equal to 480 nm and shorter than 600 nm, and wherein anemission spectrum of the third light-emitting element includes a peak ina wavelength range of longer than or equal to 400 nm and shorter than480 nm.
 13. The light-emitting device according to claim 9, wherein adistance between the first lower electrode and the first light-emittinglayer is larger than a distance between the second lower electrode andthe first light-emitting layer, and wherein a distance between thesecond lower electrode and the second light-emitting layer is largerthan a distance between the third lower electrode and the secondlight-emitting layer.
 14. The light-emitting device according to claim9, wherein an optical path length between the first lower electrode andthe first light-emitting layer is 3λ_(R)/4 when λ_(R) is a wavelength ofred light, wherein an optical path length between the second lowerelectrode and the first light-emitting layer is 3λ_(G)/4 when λ_(G) is awavelength of green light, and wherein an optical path length betweenthe third lower electrode and the second light-emitting layer is3λ_(B)/4 when λ_(B) is a wavelength of blue light.
 15. Thelight-emitting device according to claim 9, wherein the opticaladjustment layer has a hole-transport property.
 16. The light-emittingdevice according to claim 9, wherein the first light-emitting layerincludes a phosphorescent material, and wherein the secondlight-emitting layer includes a fluorescent material.